------------------------------------------------------------------------
INPUT FILE DESCRIPTION
Program: pw.x / PWscf / Quantum Espresso
------------------------------------------------------------------------
Input data format: { } = optional, [ ] = it depends, | = or
All quantities whose dimensions are not explicitly specified are in
RYDBERG ATOMIC UNITS. Charge is "number" charge (i.e. not multiplied
by e); potentials are in energy units (i.e. they are multiplied by e)
BEWARE: TABS, DOS <CR><LF> CHARACTERS ARE POTENTIAL SOURCES OF TROUBLE
Comment lines in namelists can be introduced by a "!", exactly as in
fortran code. Comments lines in ``cards'' can be introduced by
either a "!" or a "#" character in the first position of a line.
Do not start any line in ``cards'' with a "/" character.
Structure of the input data:
===============================================================================
&CONTROL
...
/
&SYSTEM
...
/
&ELECTRONS
...
/
[ &IONS
...
/ ]
[ &CELL
...
/ ]
ATOMIC_SPECIES
X Mass_X PseudoPot_X
Y Mass_Y PseudoPot_Y
Z Mass_Z PseudoPot_Z
ATOMIC_POSITIONS { alat | bohr | crystal | angstrom | crystal_sg }
X 0.0 0.0 0.0 {if_pos(1) if_pos(2) if_pos(3)}
Y 0.5 0.0 0.0
Z O.0 0.2 0.2
K_POINTS { tpiba | automatic | crystal | gamma | tpiba_b | crystal_b | tpiba_c | crystal_c }
if (gamma)
nothing to read
if (automatic)
nk1, nk2, nk3, k1, k2, k3
if (not automatic)
nks
xk_x, xk_y, xk_z, wk
[ CELL_PARAMETERS { alat | bohr | angstrom }
v1(1) v1(2) v1(3)
v2(1) v2(2) v2(3)
v3(1) v3(2) v3(3) ]
[ OCCUPATIONS
f_inp1(1) f_inp1(2) f_inp1(3) ... f_inp1(10)
f_inp1(11) f_inp1(12) ... f_inp1(nbnd)
[ f_inp2(1) f_inp2(2) f_inp2(3) ... f_inp2(10)
f_inp2(11) f_inp2(12) ... f_inp2(nbnd) ] ]
[ CONSTRAINTS
nconstr { constr_tol }
constr_type(.) constr(1,.) constr(2,.) [ constr(3,.) constr(4,.) ] { constr_target(.) } ]
[ ATOMIC_FORCES
label_1 Fx(1) Fy(1) Fz(1)
.....
label_n Fx(n) Fy(n) Fz(n) ]
========================================================================
NAMELIST: &CONTROL
+--------------------------------------------------------------------
Variable: calculation
Type: CHARACTER
Default: 'scf'
Description: a string describing the task to be performed:
'scf',
'nscf',
'bands',
'relax',
'md',
'vc-relax',
'vc-md'
(vc = variable-cell).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: title
Type: CHARACTER
Default: ' '
Description: reprinted on output.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: verbosity
Type: CHARACTER
Default: 'low'
Description: Currently two verbosity levels are implemented:
'high' and 'low'. 'debug' and 'medium' have the same
effect as 'high'; 'default' and 'minimal', as 'low'
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: restart_mode
Type: CHARACTER
Default: 'from_scratch'
Description: 'from_scratch' : from scratch. This is the normal way
to perform a PWscf calculation
'restart' : from previous interrupted run. Use this
switch only if you want to continue an
interrupted calculation, not to start a
new one, or to perform non-scf calculations.
Works only if the calculation was cleanly
stopped using variable "max_seconds", or
by user request with an "exit file" (i.e.:
create a file "prefix".EXIT, in directory
"outdir"; see variables "prefix", "outdir").
Overrides "startingwfc" and "startingpot".
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: wf_collect
Type: LOGICAL
Default: .FALSE.
Description: This flag controls the way wavefunctions are stored to disk :
.TRUE. collect wavefunctions from all processors, store them
into the output data directory "outdir"/"prefix".save,
one wavefunction per k-point in subdirs K000001/,
K000001/, etc.. Use this if you want wavefunctions
to be readable on a different number of processors.
.FALSE. do not collect wavefunctions, leave them in temporary
local files (one per processor). The resulting format
will be readable only by jobs running on the same
number of processors and pools. Requires less I/O
than the previous case.
Note that this flag has no effect on reading, only on writing.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nstep
Type: INTEGER
Description: number of ionic + electronic steps
Default: 1 if calculation = 'scf', 'nscf', 'bands';
50 for the other cases
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: iprint
Type: INTEGER
Default: write only at convergence
Description: band energies are written every "iprint" iterations
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: tstress
Type: LOGICAL
Default: .false.
Description: calculate stress. It is set to .TRUE. automatically if
calculation='vc-md' or 'vc-relax'
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: tprnfor
Type: LOGICAL
Description: calculate forces. It is set to .TRUE. automatically if
calculation='relax','md','vc-md'
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: dt
Type: REAL
Default: 20.D0
Description: time step for molecular dynamics, in Rydberg atomic units
(1 a.u.=4.8378 * 10^-17 s : beware, the CP code uses
Hartree atomic units, half that much!!!)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: outdir
Type: CHARACTER
Default: value of the ESPRESSO_TMPDIR environment variable if set;
current directory ('./') otherwise
Description: input, temporary, output files are found in this directory,
see also "wfcdir"
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: wfcdir
Type: CHARACTER
Default: same as "outdir"
Description: this directory specifies where to store files generated by
each processor (*.wfc{N}, *.igk{N}, etc.). Useful for
machines without a parallel file system: set "wfcdir" to
a local file system, while "outdir" should be a parallel
or networkfile system, visible to all processors. Beware:
in order to restart from interrupted runs, or to perform
further calculations using the produced data files, you
may need to copy files to "outdir". Works only for pw.x.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: prefix
Type: CHARACTER
Default: 'pwscf'
Description: prepended to input/output filenames:
prefix.wfc, prefix.rho, etc.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: lkpoint_dir
Type: LOGICAL
Default: .true.
Description: If .false. a subdirectory for each k_point is not opened
in the "prefix".save directory; Kohn-Sham eigenvalues are
stored instead in a single file for all k-points. Currently
doesn't work together with "wf_collect"
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: max_seconds
Type: REAL
Default: 1.D+7, or 150 days, i.e. no time limit
Description: jobs stops after "max_seconds" CPU time. Use this option
in conjunction with option "restart_mode" if you need to
split a job too long to complete into shorter jobs that
fit into your batch queues.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: etot_conv_thr
Type: REAL
Default: 1.0D-4
Description: convergence threshold on total energy (a.u) for ionic
minimization: the convergence criterion is satisfied
when the total energy changes less than "etot_conv_thr"
between two consecutive scf steps. Note that "etot_conv_thr"
is extensive, like the total energy.
See also "forc_conv_thr" - both criteria must be satisfied
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: forc_conv_thr
Type: REAL
Default: 1.0D-3
Description: convergence threshold on forces (a.u) for ionic minimization:
the convergence criterion is satisfied when all components of
all forces are smaller than "forc_conv_thr".
See also "etot_conv_thr" - both criteria must be satisfied
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: disk_io
Type: CHARACTER
Default: see below
Description: Specifies the amount of disk I/O activity
'high': save all data to disk at each SCF step
'medium': save wavefunctions at each SCF step unless
there is a single k-point per process (in which
case the behavior is the same as 'low')
'low' : store wfc in memory, save only at the end
'none': do not save anything, not even at the end
('scf', 'nscf', 'bands' calculations; some data
may be written anyway for other calculations)
Default is 'low' for the scf case, 'medium' otherwise.
Note that the needed RAM increases as disk I/O decreases!
It is no longer needed to specify 'high' in order to be able
to restart from an interrupted calculation (see "restart_mode")
but you cannot restart in disk_io='none'
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: pseudo_dir
Type: CHARACTER
Default: value of the $ESPRESSO_PSEUDO environment variable if set;
'$HOME/espresso/pseudo/' otherwise
Description: directory containing pseudopotential files
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: tefield
Type: LOGICAL
Default: .FALSE.
Description: If .TRUE. a saw-like potential simulating an electric field
is added to the bare ionic potential. See variables "edir",
"eamp", "emaxpos", "eopreg" for the form and size of
the added potential.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: dipfield
Type: LOGICAL
Default: .FALSE.
Description: If .TRUE. and tefield=.TRUE. a dipole correction is also
added to the bare ionic potential - implements the recipe
of L. Bengtsson, PRB 59, 12301 (1999). See variables "edir",
"emaxpos", "eopreg" for the form of the correction. Must
be used ONLY in a slab geometry, for surface calculations,
with the discontinuity FALLING IN THE EMPTY SPACE.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: lelfield
Type: LOGICAL
Default: .FALSE.
Description: If .TRUE. a homogeneous finite electric field described
through the modern theory of the polarization is applied.
This is different from "tefield=.true." !
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nberrycyc
Type: INTEGER
Default: 1
Description: In the case of a finite electric field ( lelfield == .TRUE. )
it defines the number of iterations for converging the
wavefunctions in the electric field Hamiltonian, for each
external iteration on the charge density
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: lorbm
Type: LOGICAL
Default: .FALSE.
Description: If .TRUE. perform orbital magnetization calculation.
If finite electric field is applied (lelfield=.true.)
only Kubo terms are computed
[for details see New J. Phys. 12, 053032 (2010)].
The type of calculation is 'nscf' and should be performed
on an automatically generated uniform grid of k points.
Works ONLY with norm-conserving pseudopotentials.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: lberry
Type: LOGICAL
Default: .FALSE.
Description: If .TRUE. perform a Berry phase calculation
See the header of PW/src/bp_c_phase.f90 for documentation
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: gdir
Type: INTEGER
Description: For Berry phase calculation: direction of the k-point
strings in reciprocal space. Allowed values: 1, 2, 3
1=first, 2=second, 3=third reciprocal lattice vector
For calculations with finite electric fields
(lelfield==.true.) "gdir" is the direction of the field
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nppstr
Type: INTEGER
Description: For Berry phase calculation: number of k-points to be
calculated along each symmetry-reduced string
The same for calculation with finite electric fields
(lelfield=.true.)
+--------------------------------------------------------------------
===END OF NAMELIST======================================================
========================================================================
NAMELIST: &SYSTEM
+--------------------------------------------------------------------
Variable: ibrav
Type: INTEGER
Status: REQUIRED
Description: Bravais-lattice index. If ibrav /= 0, specify EITHER
[ celldm(1)-celldm(6) ] OR [ A,B,C,cosAB,cosAC,cosBC ]
but NOT both. The lattice parameter "alat" is set to
alat = celldm(1) (in a.u.) or alat = A (in Angstrom);
see below for the other parameters.
For ibrav=0 specify the lattice vectors in CELL_PARAMETER,
optionally the lattice parameter alat = celldm(1) (in a.u.)
or = A (in Angstrom), or else it is taken from CELL_PARAMETERS
ibrav structure celldm(2)-celldm(6)
or: b,c,cosab,cosac,cosbc
0 free
crystal axis provided in input: see card CELL_PARAMETERS
1 cubic P (sc)
v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,1)
2 cubic F (fcc)
v1 = (a/2)(-1,0,1), v2 = (a/2)(0,1,1), v3 = (a/2)(-1,1,0)
3 cubic I (bcc)
v1 = (a/2)(1,1,1), v2 = (a/2)(-1,1,1), v3 = (a/2)(-1,-1,1)
4 Hexagonal and Trigonal P celldm(3)=c/a
v1 = a(1,0,0), v2 = a(-1/2,sqrt(3)/2,0), v3 = a(0,0,c/a)
5 Trigonal R, 3fold axis c celldm(4)=cos(alpha)
The crystallographic vectors form a three-fold star around
the z-axis, the primitive cell is a simple rhombohedron:
v1 = a(tx,-ty,tz), v2 = a(0,2ty,tz), v3 = a(-tx,-ty,tz)
where c=cos(alpha) is the cosine of the angle alpha between
any pair of crystallographic vectors, tx, ty, tz are:
tx=sqrt((1-c)/2), ty=sqrt((1-c)/6), tz=sqrt((1+2c)/3)
-5 Trigonal R, 3fold axis <111> celldm(4)=cos(alpha)
The crystallographic vectors form a three-fold star around
<111>. Defining a' = a/sqrt(3) :
v1 = a' (u,v,v), v2 = a' (v,u,v), v3 = a' (v,v,u)
where u and v are defined as
u = tz - 2*sqrt(2)*ty, v = tz + sqrt(2)*ty
and tx, ty, tz as for case ibrav=5
Note: if you prefer x,y,z as axis in the cubic limit,
set u = tz + 2*sqrt(2)*ty, v = tz - sqrt(2)*ty
See also the note in flib/latgen.f90
6 Tetragonal P (st) celldm(3)=c/a
v1 = a(1,0,0), v2 = a(0,1,0), v3 = a(0,0,c/a)
7 Tetragonal I (bct) celldm(3)=c/a
v1=(a/2)(1,-1,c/a), v2=(a/2)(1,1,c/a), v3=(a/2)(-1,-1,c/a)
8 Orthorhombic P celldm(2)=b/a
celldm(3)=c/a
v1 = (a,0,0), v2 = (0,b,0), v3 = (0,0,c)
9 Orthorhombic base-centered(bco) celldm(2)=b/a
celldm(3)=c/a
v1 = (a/2, b/2,0), v2 = (-a/2,b/2,0), v3 = (0,0,c)
-9 as 9, alternate description
v1 = (a/2,-b/2,0), v2 = (a/2,-b/2,0), v3 = (0,0,c)
10 Orthorhombic face-centered celldm(2)=b/a
celldm(3)=c/a
v1 = (a/2,0,c/2), v2 = (a/2,b/2,0), v3 = (0,b/2,c/2)
11 Orthorhombic body-centered celldm(2)=b/a
celldm(3)=c/a
v1=(a/2,b/2,c/2), v2=(-a/2,b/2,c/2), v3=(-a/2,-b/2,c/2)
12 Monoclinic P, unique axis c celldm(2)=b/a
celldm(3)=c/a,
celldm(4)=cos(ab)
v1=(a,0,0), v2=(b*cos(gamma),b*sin(gamma),0), v3 = (0,0,c)
where gamma is the angle between axis a and b.
-12 Monoclinic P, unique axis b celldm(2)=b/a
celldm(3)=c/a,
celldm(5)=cos(ac)
v1 = (a,0,0), v2 = (0,b,0), v3 = (c*cos(beta),0,c*sin(beta))
where beta is the angle between axis a and c
13 Monoclinic base-centered celldm(2)=b/a
celldm(3)=c/a,
celldm(4)=cos(ab)
v1 = ( a/2, 0, -c/2),
v2 = (b*cos(gamma), b*sin(gamma), 0),
v3 = ( a/2, 0, c/2),
where gamma is the angle between axis a and b
14 Triclinic celldm(2)= b/a,
celldm(3)= c/a,
celldm(4)= cos(bc),
celldm(5)= cos(ac),
celldm(6)= cos(ab)
v1 = (a, 0, 0),
v2 = (b*cos(gamma), b*sin(gamma), 0)
v3 = (c*cos(beta), c*(cos(alpha)-cos(beta)cos(gamma))/sin(gamma),
c*sqrt( 1 + 2*cos(alpha)cos(beta)cos(gamma)
- cos(alpha)^2-cos(beta)^2-cos(gamma)^2 )/sin(gamma) )
where alpha is the angle between axis b and c
beta is the angle between axis a and c
gamma is the angle between axis a and b
+--------------------------------------------------------------------
///---
EITHER:
+--------------------------------------------------------------------
Variable: celldm(i), i=1,6
Type: REAL
See: ibrav
Description: Crystallographic constants - see the "ibrav" variable.
Specify either these OR A,B,C,cosAB,cosBC,cosAC NOT both.
Only needed values (depending on "ibrav") must be specified
alat = celldm(1) is the lattice parameter "a" (in BOHR)
If ibrav=0, only celldm(1) is used if present;
cell vectors are read from card CELL_PARAMETERS
+--------------------------------------------------------------------
OR:
+--------------------------------------------------------------------
Variables: A, B, C, cosAB, cosAC, cosBC
Type: REAL
Description: Traditional crystallographic constants: a,b,c in ANGSTROM
cosAB = cosine of the angle between axis a and b (gamma)
cosAC = cosine of the angle between axis a and c (beta)
cosBC = cosine of the angle between axis b and c (alpha)
The axis are chosen according to the value of "ibrav".
Specify either these OR "celldm" but NOT both.
Only needed values (depending on "ibrav") must be specified
The lattice parameter alat = A (in ANGSTROM )
If ibrav = 0, only A is used if present;
cell vectors are read from card CELL_PARAMETERS
+--------------------------------------------------------------------
\\\---
+--------------------------------------------------------------------
Variable: nat
Type: INTEGER
Status: REQUIRED
Description: number of atoms in the unit cell
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: ntyp
Type: INTEGER
Status: REQUIRED
Description: number of types of atoms in the unit cell
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nbnd
Type: INTEGER
Default: for an insulator, nbnd = number of valence bands
(nbnd = # of electrons /2);
for a metal, 20% more (minimum 4 more)
Description: number of electronic states (bands) to be calculated.
Note that in spin-polarized calculations the number of
k-point, not the number of bands per k-point, is doubled
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: tot_charge
Type: REAL
Default: 0.0
Description: total charge of the system. Useful for simulations with charged cells.
By default the unit cell is assumed to be neutral (tot_charge=0).
tot_charge=+1 means one electron missing from the system,
tot_charge=-1 means one additional electron, and so on.
In a periodic calculation a compensating jellium background is
inserted to remove divergences if the cell is not neutral.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: tot_magnetization
Type: REAL
Default: -1 [unspecified]
Description: total majority spin charge - minority spin charge.
Used to impose a specific total electronic magnetization.
If unspecified then tot_magnetization variable is ignored and
the amount of electronic magnetization is determined during
the self-consistent cycle.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: starting_magnetization(i), i=1,ntyp
Type: REAL
Description: starting spin polarization on atomic type 'i' in a spin
polarized calculation. Values range between -1 (all spins
down for the valence electrons of atom type 'i') to 1
(all spins up). Breaks the symmetry and provides a starting
point for self-consistency. The default value is zero, BUT a
value MUST be specified for AT LEAST one atomic type in spin
polarized calculations, unless you constrain the magnetization
(see "tot_magnetization" and "constrained_magnetization").
Note that if you start from zero initial magnetization, you
will invariably end up in a nonmagnetic (zero magnetization)
state. If you want to start from an antiferromagnetic state,
you may need to define two different atomic species
corresponding to sublattices of the same atomic type.
starting_magnetization is ignored if you are performing a
non-scf calculation, if you are restarting from a previous
run, or restarting from an interrupted run.
If you fix the magnetization with "tot_magnetization",
you should not specify starting_magnetization.
In the spin-orbit case starting with zero
starting_magnetization on all atoms imposes time reversal
symmetry. The magnetization is never calculated and
kept zero (the internal variable domag is .FALSE.).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: ecutwfc
Type: REAL
Status: REQUIRED
Description: kinetic energy cutoff (Ry) for wavefunctions
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: ecutrho
Type: REAL
Default: 4 * ecutwfc
Description: kinetic energy cutoff (Ry) for charge density and potential
For norm-conserving pseudopotential you should stick to the
default value, you can reduce it by a little but it will
introduce noise especially on forces and stress.
If there are ultrasoft PP, a larger value than the default is
often desirable (ecutrho = 8 to 12 times ecutwfc, typically).
PAW datasets can often be used at 4*ecutwfc, but it depends
on the shape of augmentation charge: testing is mandatory.
The use of gradient-corrected functional, especially in cells
with vacuum, or for pseudopotential without non-linear core
correction, usually requires an higher values of ecutrho
to be accurately converged.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: ecutfock
Type: REAL
Default: ecutrho
Description: kinetic energy cutoff (Ry) for the exact exchange operator in
EXX type calculations. By default this is the same as ecutrho
but in some EXX calculations significant speed-up can be found
by reducing ecutfock, at the expense of some loss in accuracy.
Must be .gt. ecutwfc. Not implemented for stress calculation.
Use with care, especially in metals where it may give raise
to instabilities.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: nr1, nr2, nr3
Type: INTEGER
Description: three-dimensional FFT mesh (hard grid) for charge
density (and scf potential). If not specified
the grid is calculated based on the cutoff for
charge density (see also "ecutrho")
Note: you must specify all three dimensions for this setting to
be used.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: nr1s, nr2s, nr3s
Type: INTEGER
Description: three-dimensional mesh for wavefunction FFT and for the smooth
part of charge density ( smooth grid ).
Coincides with nr1, nr2, nr3 if ecutrho = 4 * ecutwfc ( default )
Note: you must specify all three dimensions for this setting to
be used.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nosym
Type: LOGICAL
Default: .FALSE.
Description: if (.TRUE.) symmetry is not used. Note that
- if the k-point grid is provided in input, it is used "as is"
and symmetry-inequivalent k-points are not generated;
- if the k-point grid is automatically generated, it will
contain only points in the irreducible BZ for the bravais
lattice, irrespective of the actual crystal symmetry.
A careful usage of this option can be advantageous
- in low-symmetry large cells, if you cannot afford a k-point
grid with the correct symmetry
- in MD simulations
- in calculations for isolated atoms
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nosym_evc
Type: LOGICAL
Default: .FALSE.
Description: if(.TRUE.) symmetry is not used but the k-points are
forced to have the symmetry of the Bravais lattice;
an automatically generated k-point grid will contain
all the k-points of the grid and the points rotated by
the symmetries of the Bravais lattice which are not in the
original grid. If available, time reversal is
used to reduce the k-points (and the q => -q symmetry
is used in the phonon code). To disable also this symmetry set
noinv=.TRUE..
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: noinv
Type: LOGICAL
Default: .FALSE.
Description: if (.TRUE.) disable the usage of k => -k symmetry
(time reversal) in k-point generation
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: no_t_rev
Type: LOGICAL
Default: .FALSE.
Description: if (.TRUE.) disable the usage of magnetic symmetry operations
that consist in a rotation + time reversal.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: force_symmorphic
Type: LOGICAL
Default: .FALSE.
Description: if (.TRUE.) force the symmetry group to be symmorphic by disabling
symmetry operations having an associated fractionary translation
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: use_all_frac
Type: LOGICAL
Default: .FALSE.
Description: if (.TRUE.) do not discard symmetry operations with an
associated fractionary translation that does not send the
real-space FFT grid into itself. These operations are
incompatible with real-space symmetrization but not with the
new G-space symmetrization. BEWARE: do not use for phonons!
The phonon code still uses real-space symmetrization.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: occupations
Type: CHARACTER
Description: 'smearing': gaussian smearing for metals
see variables 'smearing' and 'degauss'
'tetrahedra' : especially suited for calculation of DOS
(see P.E. Bloechl, PRB49, 16223 (1994))
Requires uniform grid of k-points,
automatically generated (see below)
Not suitable (because not variational) for
force/optimization/dynamics calculations
'fixed' : for insulators with a gap
'from_input' : The occupation are read from input file,
card OCCUPATIONS. Option valid only for a
single k-point, requires "nbnd" to be set
in input. Occupations should be consistent
with the value of "tot_charge".
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: one_atom_occupations
Type: LOGICAL
Default: .FALSE.
Description: This flag is used for isolated atoms (nat=1) together with
occupations='from_input'. If it is .TRUE., the wavefunctions
are ordered as the atomic starting wavefunctions, independently
from their eigenvalue. The occupations indicate which atomic
states are filled.
The order of the states is written inside the UPF
pseudopotential file.
In the scalar relativistic case:
S -> l=0, m=0
P -> l=1, z, x, y
D -> l=2, r^2-3z^2, xz, yz, xy, x^2-y^2
In the noncollinear magnetic case (with or without spin-orbit),
each group of states is doubled. For instance:
P -> l=1, z, x, y for spin up, l=1, z, x, y for spin down.
Up and down is relative to the direction of the starting
magnetization.
In the case with spin-orbit and time-reversal
(starting_magnetization=0.0) the atomic wavefunctions are
radial functions multiplied by spin-angle functions.
For instance:
P -> l=1, j=1/2, m_j=-1/2,1/2. l=1, j=3/2,
m_j=-3/2, -1/2, 1/2, 3/2.
In the magnetic case with spin-orbit the atomic wavefunctions
can be forced to be spin-angle functions by setting
starting_spin_angle to .TRUE..
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: starting_spin_angle
Type: LOGICAL
Default: .FALSE.
Description: In the spin-orbit case when domag=.TRUE., by default,
the starting wavefunctions are initialized as in scalar
relativistic noncollinear case without spin-orbit.
By setting starting_spin_angle=.TRUE. this behaviour can
be changed and the initial wavefunctions are radial
functions multiplied by spin-angle functions.
When domag=.FALSE. the initial wavefunctions are always
radial functions multiplied by spin-angle functions
independently from this flag.
When lspinorb is .FALSE. this flag is not used.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: degauss
Type: REAL
Default: 0.D0 Ry
Description: value of the gaussian spreading (Ry) for brillouin-zone
integration in metals.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: smearing
Type: CHARACTER
Default: 'gaussian'
Description: 'gaussian', 'gauss':
ordinary Gaussian spreading (Default)
'methfessel-paxton', 'm-p', 'mp':
Methfessel-Paxton first-order spreading
(see PRB 40, 3616 (1989)).
'marzari-vanderbilt', 'cold', 'm-v', 'mv':
Marzari-Vanderbilt cold smearing
(see PRL 82, 3296 (1999))
'fermi-dirac', 'f-d', 'fd':
smearing with Fermi-Dirac function
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nspin
Type: INTEGER
Default: 1
Description: nspin = 1 : non-polarized calculation (default)
nspin = 2 : spin-polarized calculation, LSDA
(magnetization along z axis)
nspin = 4 : spin-polarized calculation, noncollinear
(magnetization in generic direction)
DO NOT specify nspin in this case;
specify "noncolin=.TRUE." instead
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: noncolin
Type: LOGICAL
Default: .false.
Description: if .true. the program will perform a noncollinear calculation.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: ecfixed
Type: REAL
Default: 0.0
See: q2sigma
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: qcutz
Type: REAL
Default: 0.0
See: q2sigma
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: q2sigma
Type: REAL
Default: 0.1
Description: ecfixed, qcutz, q2sigma: parameters for modified functional to be
used in variable-cell molecular dynamics (or in stress calculation).
"ecfixed" is the value (in Rydberg) of the constant-cutoff;
"qcutz" and "q2sigma" are the height and the width (in Rydberg)
of the energy step for reciprocal vectors whose square modulus
is greater than "ecfixed". In the kinetic energy, G^2 is
replaced by G^2 + qcutz * (1 + erf ( (G^2 - ecfixed)/q2sigma) )
See: M. Bernasconi et al, J. Phys. Chem. Solids 56, 501 (1995)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: input_dft
Type: CHARACTER
Default: read from pseudopotential files
Description: Exchange-correlation functional: eg 'PBE', 'BLYP' etc
See Modules/functionals.f90 for allowed values.
Overrides the value read from pseudopotential files.
Use with care and if you know what you are doing!
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: exx_fraction
Type: REAL
Default: it depends on the specified functional
Description: Fraction of EXX for hybrid functional calculations. In the case of
input_dft='PBE0', the default value is 0.25, while for input_dft='B3LYP'
the exx_fraction default value is 0.20.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: screening_parameter
Type: REAL
Default: 0.106
Description: screening_parameter for HSE like hybrid functionals.
See J. Chem. Phys. 118, 8207 (2003)
and J. Chem. Phys. 124, 219906 (2006) for more informations.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: exxdiv_treatment
Type: CHARACTER
Default: gygi-baldereschi
Description: Specific for EXX. It selects the kind of approach to be used
for treating the Coulomb potential divergencies at small q vectors.
gygi-baldereschi : appropriate for cubic and quasi-cubic supercells
vcut_spherical : appropriate for cubic and quasi-cubic supercells
vcut_ws : appropriate for strongly anisotropic supercells, see also
ecutvcut.
none : sets Coulomb potential at G,q=0 to 0.0 (required for GAU-PBE)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: x_gamma_extrapolation
Type: LOGICAL
Default: .true.
Description: Specific for EXX. If true, extrapolate the G=0 term of the
potential (see README in examples/EXX_example for more)
Set this to .false. for GAU-PBE.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: ecutvcut
Type: REAL
Default: 0.0 Ry
See: exxdiv_treatment
Description: Reciprocal space cutoff for correcting
Coulomb potential divergencies at small q vectors.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: nqx1, nqx2, nqx3
Type: INTEGER
Description: three-dimensional mesh for q (k1-k2) sampling of
the Fock operator (EXX). Can be smaller than
the number of k-points.
Currently this defaults to the size of the k-point mesh used.
In QE =< 5.0.2 it defaulted to nqx1=nqx2=nqx3=1.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: lda_plus_u
Type: LOGICAL
Default: .FALSE.
Status: DFT+U (formerly known as LDA+U) currently works only for
a few selected elements. Modify flib/set_hubbard_l.f90 and
PW/src/tabd.f90 if you plan to use DFT+U with an element that
is not configured there.
Description: Specify lda_plus_u = .TRUE. to enable DFT+U calculations
See: Anisimov, Zaanen, and Andersen, PRB 44, 943 (1991);
Anisimov et al., PRB 48, 16929 (1993);
Liechtenstein, Anisimov, and Zaanen, PRB 52, R5467 (1994).
You must specify, for each species with a U term, the value of
U and (optionally) alpha, J of the Hubbard model (all in eV):
see lda_plus_u_kind, Hubbard_U, Hubbard_alpha, Hubbard_J
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: lda_plus_u_kind
Type: INTEGER
Default: 0
Description: Specifies the type of DFT+U calculation:
0 simplified version of Cococcioni and de Gironcoli,
PRB 71, 035105 (2005), using Hubbard_U
1 rotationally invariant scheme of Liechtenstein et al.,
using Hubbard_U and Hubbard_J
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: Hubbard_U(i), i=1,ntyp
Type: REAL
Default: 0.D0 for all species
Description: Hubbard_U(i): U parameter (eV) for species i, DFT+U calculation
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: Hubbard_J0(i), i=1,ntype
Type: REAL
Default: 0.D0 for all species
Description: Hubbard_J0(i): J0 parameter (eV) for species i, DFT+U+J calculation,
see PRB 84, 115108 (2011) for details.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: Hubbard_alpha(i), i=1,ntyp
Type: REAL
Default: 0.D0 for all species
Description: Hubbard_alpha(i) is the perturbation (on atom i, in eV)
used to compute U with the linear-response method of
Cococcioni and de Gironcoli, PRB 71, 35105 (2005)
(only for lda_plus_u_kind=0)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: Hubbard_beta(i), i=1,ntyp
Type: REAL
Default: 0.D0 for all species
Description: Hubbard_beta(i) is the perturbation (on atom i, in eV)
used to compute J0 with the linear-response method of
Cococcioni and de Gironcoli, PRB 71, 35105 (2005)
(only for lda_plus_u_kind=0). See also
PRB 84, 115108 (2011).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: Hubbard_J(i,ityp)
Default: 0.D0 for all species
Description: Hubbard_J(i,ityp): J parameters (eV) for species ityp,
used in DFT+U calculations (only for lda_plus_u_kind=1)
For p orbitals: J = Hubbard_J(1,ityp);
For d orbitals: J = Hubbard_J(1,ityp), B = Hubbard_J(2,ityp);
For f orbitals: J = Hubbard_J(1,ityp), E2 = Hubbard_J(2,ityp),
E3= Hubbard_J(3,ityp).
If B or E2 or E3 are not specified or set to 0 they will be
calculated from J using atomic ratios.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: starting_ns_eigenvalue(m,ispin,I)
Type: REAL
Default: -1.d0 that means NOT SET
Description: In the first iteration of an DFT+U run it overwrites
the m-th eigenvalue of the ns occupation matrix for the
ispin component of atomic species I. Leave unchanged
eigenvalues that are not set. This is useful to suggest
the desired orbital occupations when the default choice
takes another path.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: U_projection_type
Type: CHARACTER
Default: 'atomic'
Description: Only active when lda_plus_U is .true., specifies the type
of projector on localized orbital to be used in the DFT+U
scheme.
Currently available choices:
'atomic': use atomic wfc's (as they are) to build the projector
'ortho-atomic': use Lowdin orthogonalized atomic wfc's
'norm-atomic': Lowdin normalization of atomic wfc. Keep in mind:
atomic wfc are not orthogonalized in this case.
This is a "quick and dirty" trick to be used when
atomic wfc from the pseudopotential are not
normalized (and thus produce occupation whose
value exceeds unity). If orthogonalized wfc are
not needed always try 'atomic' first.
'file': use the information from file "prefix".atwfc that must
have been generated previously, for instance by pmw.x
(see PP/src/poormanwannier.f90 for details).
'pseudo': use the pseudopotential projectors. The charge density
outside the atomic core radii is excluded.
N.B.: for atoms with +U, a pseudopotential with the
all-electron atomic wavefunctions is required (i.e.,
as generated by ld1.x with lsave_wfc flag).
NB: forces and stress currently implemented only for the
'atomic' and 'pseudo' choice.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: edir
Type: INTEGER
Description: The direction of the electric field or dipole correction is
parallel to the bg(:,edir) reciprocal lattice vector, so the
potential is constant in planes defined by FFT grid points;
edir = 1, 2 or 3. Used only if tefield is .TRUE.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: emaxpos
Type: REAL
Default: 0.5D0
Description: Position of the maximum of the saw-like potential along crystal
axis "edir", within the unit cell (see below), 0 < emaxpos < 1
Used only if tefield is .TRUE.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: eopreg
Type: REAL
Default: 0.1D0
Description: Zone in the unit cell where the saw-like potential decreases.
( see below, 0 < eopreg < 1 ). Used only if tefield is .TRUE.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: eamp
Type: REAL
Default: 0.001 a.u.
Description: Amplitude of the electric field, in ***Hartree*** a.u.;
1 a.u. = 51.4220632*10^10 V/m). Used only if tefield=.TRUE.
The saw-like potential increases with slope "eamp" in the
region from (emaxpos+eopreg-1) to (emaxpos), then decreases
to 0 until (emaxpos+eopreg), in units of the crystal
vector "edir". Important: the change of slope of this
potential must be located in the empty region, or else
unphysical forces will result.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: angle1(i), i=1,ntyp
Type: REAL
Description: The angle expressed in degrees between the initial
magnetization and the z-axis. For noncollinear calculations
only; index i runs over the atom types.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: angle2(i), i=1,ntyp
Type: REAL
Description: The angle expressed in degrees between the projection
of the initial magnetization on x-y plane and the x-axis.
For noncollinear calculations only.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: constrained_magnetization
Type: CHARACTER
See: lambda, fixed_magnetization
Default: 'none'
Description: Used to perform constrained calculations in magnetic systems.
Currently available choices:
'none':
no constraint
'total':
total magnetization is constrained by
adding a penalty functional to the total energy:
LAMBDA * SUM_{i} ( magnetization(i) - fixed_magnetization(i) )**2
where the sum over i runs over the three components of
the magnetization. Lambda is a real number (see below).
Noncolinear case only. Use "tot_magnetization" for LSDA
'atomic':
atomic magnetization are constrained to the defined
starting magnetization adding a penalty:
LAMBDA * SUM_{i,itype} ( magnetic_moment(i,itype) - mcons(i,itype) )**2
where i runs over the cartesian components (or just z
in the collinear case) and itype over the types (1-ntype).
mcons(:,:) array is defined from starting_magnetization,
(and angle1, angle2 in the non-collinear case). lambda is
a real number
'total direction':
the angle theta of the total magnetization
with the z axis (theta = fixed_magnetization(3))
is constrained:
LAMBDA * ( arccos(magnetization(3)/mag_tot) - theta )**2
where mag_tot is the modulus of the total magnetization.
'atomic direction':
not all the components of the atomic
magnetic moment are constrained but only the cosine
of angle1, and the penalty functional is:
LAMBDA * SUM_{itype} ( mag_mom(3,itype)/mag_mom_tot - cos(angle1(ityp)) )**2
N.B.: symmetrization may prevent to reach the desired orientation
of the magnetization. Try not to start with very highly symmetric
configurations or use the nosym flag (only as a last remedy)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: fixed_magnetization(i), i=1,3
Type: REAL
See: constrained_magnetization
Default: 0.d0
Description: total magnetization vector (x,y,z components) to be kept
fixed when constrained_magnetization='total'
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: lambda
Type: REAL
See: constrained_magnetization
Default: 1.d0
Description: parameter used for constrained_magnetization calculations
N.B.: if the scf calculation does not converge, try to reduce lambda
to obtain convergence, then restart the run with a larger lambda
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: report
Type: INTEGER
Default: 1
Description: It is the number of iterations after which the program
write all the atomic magnetic moments.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: lspinorb
Type: LOGICAL
Description: if .TRUE. the noncollinear code can use a pseudopotential with
spin-orbit.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: assume_isolated
Type: CHARACTER
Default: 'none'
Description: Used to perform calculation assuming the system to be
isolated (a molecule or a cluster in a 3D supercell).
Currently available choices:
'none' (default): regular periodic calculation w/o any correction.
'makov-payne', 'm-p', 'mp' : the Makov-Payne correction to the
total energy is computed. An estimate of the vacuum
level is also calculated so that eigenvalues can be
properly aligned. ONLY FOR CUBIC SYSTEMS (ibrav=1,2,3)
Theory:
G.Makov, and M.C.Payne,
"Periodic boundary conditions in ab initio
calculations" , Phys.Rev.B 51, 4014 (1995)
'martyna-tuckerman', 'm-t', 'mt' : Martyna-Tuckerman correction
to both total energy and scf potential. Adapted from:
G.J. Martyna, and M.E. Tuckerman,
"A reciprocal space based method for treating long
range interactions in ab-initio and force-field-based
calculation in clusters", J.Chem.Phys. 110, 2810 (1999)
'esm' : Effective Screening Medium Method.
For polarized or charged slab calculation, embeds
the simulation cell within an effective semi-
infinite medium in the perpendicular direction
(along z). Embedding regions can be vacuum or
semi-infinite metal electrodes (use 'esm_bc' to
choose boundary conditions). If between two
electrodes, an optional electric field
('esm_efield') may be applied. Method described in
M. Otani and O. Sugino, "First-principles
calculations of charged surfaces and interfaces:
A plane-wave nonrepeated slab approach," PRB 73,
115407 (2006).
NB: Requires cell with a_3 lattice vector along z,
normal to the xy plane, with the slab centered
around z=0. Also requires symmetry checking to be
disabled along z, either by setting 'nosym' = .TRUE.
or by very slight displacement (i.e., 5e-4 a.u.)
of the slab along z.
See 'esm_bc', 'esm_efield', 'esm_w', 'esm_nfit'.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: esm_bc
Type: CHARACTER
See: assume_isolated
Default: 'pbc'
Description: If assume_isolated = 'esm', determines the boundary
conditions used for either side of the slab.
Currently available choices:
'pbc' (default): regular periodic calculation (no ESM).
'bc1' : Vacuum-slab-vacuum (open boundary conditions)
'bc2' : Metal-slab-metal (dual electrode configuration).
See also 'esm_efield'.
'bc3' : Vacuum-slab-metal
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: esm_w
Type: REAL
See: assume_isolated
Default: 0.d0
Description: If assume_isolated = 'esm', determines the position offset
[in a.u.] of the start of the effective screening region,
measured relative to the cell edge. (ESM region begins at
z = +/- [L_z/2 + esm_w] ).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: esm_efield
Type: REAL
See: assume_isolated, esm_bc
Default: 0.d0
Description: If assume_isolated = 'esm' and esm_bc = 'bc2', gives the
magnitude of the electric field [Ry/a.u.] to be applied
between semi-infinite ESM electrodes.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: esm_nfit
Type: INTEGER
See: assume_isolated
Default: 4
Description: If assume_isolated = 'esm', gives the number of z-grid points
for the polynomial fit along the cell edge.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: vdw_corr
Type: CHARACTER
Default: 'none'
Description: Type of Van der Waals correction. Allowed values:
'grimme-d2', 'Grimme-D2', 'DFT-D', 'dft-d': semiempirical Grimme's DFT-D2.
Optional variables: "london_s6", "london_rcut", "london_c6"
S. Grimme, J. Comp. Chem. 27, 1787 (2006),
V. Barone et al., J. Comp. Chem. 30, 934 (2009).
'TS', 'ts', 'ts-vdw', 'ts-vdW', 'tkatchenko-scheffler': Tkatchenko-Scheffler
dispersion corrections with first-principle derived C6 coefficients
(implemented in CP only). Optional variables: "ts_vdw_econv_thr", "ts_vdw_isolated"
See A. Tkatchenko and M. Scheffler, Phys. Rev. Lett. 102, 073005 (2009)
'XDM', 'xdm': Exchange-hole dipole-moment model. Optional variables: "xdm_a1", "xdm_a2"
A. D. Becke and E. R. Johnson, J. Chem. Phys. 127, 154108 (2007)
A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 136, 174109 (2012)
Note that non-local functionals (eg vdw-DF) are NOT specified here but in "input_dft"
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: london
Type: LOGICAL
Default: .FALSE.
Description: OBSOLESCENT, same as vdw_corr='DFT-D'
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: london_s6
Type: REAL
Default: 0.75
Description: global scaling parameter for DFT-D. Default is good for PBE.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: london_c6(i), i=1,ntyp
Type: REAL
Default: standard Grimme-D2 values
Description: atomic C6 coefficient of each atom type
( if not specified default values from S. Grimme, J. Comp. Chem. 27, 1787 (2006) are used;
see file Modules/mm_dispersion.f90 )
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: london_rcut
Type: REAL
Default: 200
Description: cutoff radius (a.u.) for dispersion interactions
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: xdm
Type: LOGICAL
Default: .FALSE.
Description: OBSOLESCENT, same as vdw_corr='xdm'
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: xdm_a1
Type: REAL
Default: 0.6836
Description: Damping function parameter a1 (adimensional). This value should change
with the exchange-correlation functional. The default corresponds to
PW86PBE.
For other functionals, see:
http://gatsby.ucmerced.edu/wiki/XDM_damping_function_parameters
A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 138, 204109 (2013)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: xdm_a2
Type: REAL
Default: 1.5045
Description: Damping function parameter a2 (angstrom). This value should change
with the exchange-correlation functional. The default corresponds to
PW86PBE.
For other functionals, see:
http://gatsby.ucmerced.edu/wiki/XDM_damping_function_parameters
A. Otero de la Roza, E. R. Johnson, J. Chem. Phys. 138, 204109 (2013)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: space_group
Type: INTEGER
Default: 0
Description: The number of the space group of the crystal, as given
in the International Tables of Crystallography A (ITA).
This allows to give in input only the inequivalent atomic
positions. The positions of all the symmetry equivalent atoms
are calculated by the code. Used only when the atomic positions
are of type crystal_sg.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: uniqueb
Type: LOGICAL
Default: .FALSE.
Description: Used only for monoclinic lattices. If .TRUE. the b
unique ibrav (-12 or -13) are used, and symmetry
equivalent positions are chosen assuming that the
two fold axis or the mirror normal is parallel to the
b axis. If .FALSE. it is parallel to the c axis.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: origin_choice
Type: INTEGER
Default: 1
Description: Used only for space groups that in the ITA allow
the use of two different origins. origin_choice=1,
means the first origin, while origin_choice=2 is the
second origin.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: rhombohedral
Type: LOGICAL
Default: .TRUE.
Description: Used only for rhombohedral space groups.
When .TRUE. the coordinates of the inequivalent atoms are
given with respect to the rhombohedral axes, when .FALSE.
the coordinates of the inequivalent atoms are given with
respect to the hexagonal axes. They are converted internally
to the rhombohedral axes and ibrav=5 is used in both cases.
+--------------------------------------------------------------------
===END OF NAMELIST======================================================
========================================================================
NAMELIST: &ELECTRONS
+--------------------------------------------------------------------
Variable: electron_maxstep
Type: INTEGER
Default: 100
Description: maximum number of iterations in a scf step
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: scf_must_converge
Type: LOGICAL
Default: .TRUE.
Description: If .false. do not stop molecular dynamics or ionic relaxation
when electron_maxstep is reached. Use with care.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: conv_thr
Type: REAL
Default: 1.D-6
Description: Convergence threshold for selfconsistency:
estimated energy error < conv_thr
(note that conv_thr is extensive, like the total energy).
For non-self-consistent calculations, conv_thr is used
to set the default value of the threshold (ethr) for
iterative diagonalizazion: see diago_thr_init
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: adaptive_thr
Type: LOGICAL
Default: .FALSE
Description: If .TRUE. this turns on the use of an adaptive conv_thr for
the inner scf loops when using EXX.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: conv_thr_init
Type: REAL
Default: 1.D-3
Description: When adaptive_thr = .TRUE. this is the convergence threshold
used for the first scf cycle.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: conv_thr_multi
Type: REAL
Default: 1.D-1
Description: When adaptive_thr = .TRUE. the convergence threshold for
each scf cycle is given by:
max( conv_thr, conv_thr_multi * dexx )
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: mixing_mode
Type: CHARACTER
Default: 'plain'
Description: 'plain' : charge density Broyden mixing
'TF' : as above, with simple Thomas-Fermi screening
(for highly homogeneous systems)
'local-TF': as above, with local-density-dependent TF screening
(for highly inhomogeneous systems)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: mixing_beta
Type: REAL
Default: 0.7D0
Description: mixing factor for self-consistency
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: mixing_ndim
Type: INTEGER
Default: 8
Description: number of iterations used in mixing scheme.
If you are tight with memory, you may reduce it to 4 or so.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: mixing_fixed_ns
Type: INTEGER
Default: 0
Description: For DFT+U : number of iterations with fixed ns ( ns is the
atomic density appearing in the Hubbard term ).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: diagonalization
Type: CHARACTER
Default: 'david'
Description: 'david': Davidson iterative diagonalization with overlap matrix
(default). Fast, may in some rare cases fail.
'cg' : conjugate-gradient-like band-by-band diagonalization
Typically slower than 'david' but it uses less memory
and is more robust (it seldom fails)
'cg-serial', 'david-serial': obsolete, use "-ndiag 1 instead"
The subspace diagonalization in Davidson is performed
by a fully distributed-memory parallel algorithm on
4 or more processors, by default. The allocated memory
scales down with the number of procs. Procs involved
in diagonalization can be changed with command-line
option "-ndiag N". On multicore CPUs it is often
convenient to let just one core per CPU to work
on linear algebra.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: ortho_para
Type: INTEGER
Default: 0
Status: OBSOLETE: use command-line option " -ndiag XX" instead
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: diago_thr_init
Type: REAL
Description: Convergence threshold (ethr) for iterative diagonalization
(the check is on eigenvalue convergence).
For scf calculations: default is 1.D-2 if starting from a
superposition of atomic orbitals; 1.D-5 if starting from a
charge density. During self consistency the threshold
is automatically reduced (but never below 1.D-13) when
approaching convergence.
For non-scf calculations: default is (conv_thr/N elec)/10.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: diago_cg_maxiter
Type: INTEGER
Description: For conjugate gradient diagonalization:
max number of iterations
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: diago_david_ndim
Type: INTEGER
Default: 4
Description: For Davidson diagonalization: dimension of workspace
(number of wavefunction packets, at least 2 needed).
A larger value may yield a somewhat faster algorithm
but uses more memory. The opposite holds for smaller values.
Try diago_david_ndim=2 if you are tight on memory or if
your job is large: the speed penalty is often negligible
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: diago_full_acc
Type: LOGICAL
Default: .FALSE.
Description: If .TRUE. all the empty states are diagonalized at the same level
of accuracy of the occupied ones. Otherwise the empty states are
diagonalized using a larger threshold (this should not affect
total energy, forces, and other ground-state properties).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: efield
Type: REAL
Default: 0.D0
Description: Amplitude of the finite electric field (in Ry a.u.;
1 a.u. = 36.3609*10^10 V/m). Used only if lelfield=.TRUE.
and if k-points (K_POINTS card) are not automatic.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: efield_cart(i), i=1,3
Type: REAL
Default: (0.D0, 0.D0, 0.D0)
Description: Finite electric field (in Ry a.u.=36.3609*10^10 V/m) in
cartesian axis. Used only if lelfield=.TRUE. and if
k-points (K_POINTS card) are automatic.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: startingpot
Type: CHARACTER
Description: 'atomic': starting potential from atomic charge superposition
( default for scf, *relax, *md )
'file' : start from existing "charge-density.xml" file in the
directory specified by variables "prefix" and "outdir"
For nscf and bands calculation this is the default
and the only sensible possibility.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: startingwfc
Type: CHARACTER
Default: 'atomic+random'
Description: 'atomic': start from superposition of atomic orbitals
If not enough atomic orbitals are available,
fill with random numbers the remaining wfcs
The scf typically starts better with this option,
but in some high-symmetry cases one can "loose"
valence states, ending up in the wrong ground state.
'atomic+random': as above, plus a superimposed "randomization"
of atomic orbitals. Prevents the "loss" of states
mentioned above.
'random': start from random wfcs. Slower start of scf but safe.
It may also reduce memory usage in conjunction with
diagonalization='cg'
'file': start from an existing wavefunction file in the
directory specified by variables "prefix" and "outdir"
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: tqr
Type: LOGICAL
Default: .FALSE.
Description: If .true., use the real-space algorithm for augmentation
charges in ultrasoft pseudopotentials.
Must faster execution of ultrasoft-related calculations,
but numerically less accurate than the default algorithm.
Use with care and after testing!
+--------------------------------------------------------------------
===END OF NAMELIST======================================================
========================================================================
NAMELIST: &IONS
INPUT THIS NAMELIST ONLY IF CALCULATION = 'RELAX', 'MD', 'VC-RELAX', 'VC-MD'
+--------------------------------------------------------------------
Variable: ion_dynamics
Type: CHARACTER
Description: Specify the type of ionic dynamics.
For different type of calculation different possibilities are
allowed and different default values apply:
CASE ( calculation = 'relax' )
'bfgs' : (default) use BFGS quasi-newton algorithm,
based on the trust radius procedure,
for structural relaxation
'damp' : use damped (quick-min Verlet)
dynamics for structural relaxation
Can be used for constrained
optimisation: see CONSTRAINTS card
CASE ( calculation = 'md' )
'verlet' : (default) use Verlet algorithm to integrate
Newton's equation. For constrained
dynamics, see CONSTRAINTS card
'langevin' ion dynamics is over-damped Langevin
'langevin-smc' over-damped Langevin with Smart Monte Carlo:
see R.J.Rossky, JCP, 69, 4628(1978)
CASE ( calculation = 'vc-relax' )
'bfgs' : (default) use BFGS quasi-newton algorithm;
cell_dynamics must be 'bfgs' too
'damp' : use damped (Beeman) dynamics for
structural relaxation
CASE ( calculation = 'vc-md' )
'beeman' : (default) use Beeman algorithm to integrate
Newton's equation
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: ion_positions
Type: CHARACTER
Default: 'default'
Description: 'default ' : if restarting, use atomic positions read from the
restart file; in all other cases, use atomic
positions from standard input.
'from_input' : restart the simulation with atomic positions read
from standard input, even if restarting.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: pot_extrapolation
Type: CHARACTER
Default: 'atomic'
Description: Used to extrapolate the potential from preceding ionic steps.
'none' : no extrapolation
'atomic' : extrapolate the potential as if it was a sum of
atomic-like orbitals
'first_order' : extrapolate the potential with first-order
formula
'second_order': as above, with second order formula
Note: 'first_order' and 'second-order' extrapolation make sense
only for molecular dynamics calculations
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: wfc_extrapolation
Type: CHARACTER
Default: 'none'
Description: Used to extrapolate the wavefunctions from preceding ionic steps.
'none' : no extrapolation
'first_order' : extrapolate the wave-functions with first-order
formula.
'second_order': as above, with second order formula.
Note: 'first_order' and 'second-order' extrapolation make sense
only for molecular dynamics calculations
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: remove_rigid_rot
Type: LOGICAL
Default: .FALSE.
Description: This keyword is useful when simulating the dynamics and/or the
thermodynamics of an isolated system. If set to true the total
torque of the internal forces is set to zero by adding new forces
that compensate the spurious interaction with the periodic
images. This allows for the use of smaller supercells.
BEWARE: since the potential energy is no longer consistent with
the forces (it still contains the spurious interaction with the
repeated images), the total energy is not conserved anymore.
However the dynamical and thermodynamical properties should be
in closer agreement with those of an isolated system.
Also the final energy of a structural relaxation will be higher,
but the relaxation itself should be faster.
+--------------------------------------------------------------------
///---
KEYWORDS USED FOR MOLECULAR DYNAMICS
+--------------------------------------------------------------------
Variable: ion_temperature
Type: CHARACTER
Default: 'not_controlled'
Description: 'rescaling' control ionic temperature via velocity rescaling
(first method) see parameters "tempw", "tolp", and
"nraise" (for VC-MD only). This rescaling method
is the only one currently implemented in VC-MD
'rescale-v' control ionic temperature via velocity rescaling
(second method) see parameters "tempw" and "nraise"
'rescale-T' control ionic temperature via velocity rescaling
(third method) see parameter "delta_t"
'reduce-T' reduce ionic temperature every "nraise" steps
by the (negative) value "delta_t"
'berendsen' control ionic temperature using "soft" velocity
rescaling - see parameters "tempw" and "nraise"
'andersen' control ionic temperature using Andersen thermostat
see parameters "tempw" and "nraise"
'initial' initialize ion velocities to temperature "tempw"
and leave uncontrolled further on
'not_controlled' (default) ionic temperature is not controlled
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: tempw
Type: REAL
Default: 300.D0
Description: Starting temperature (Kelvin) in MD runs
target temperature for most thermostats.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: tolp
Type: REAL
Default: 100.D0
Description: Tolerance for velocity rescaling. Velocities are rescaled if
the run-averaged and target temperature differ more than tolp.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: delta_t
Type: REAL
Default: 1.D0
Description: if ion_temperature='rescale-T':
at each step the instantaneous temperature is multiplied
by delta_t; this is done rescaling all the velocities.
if ion_temperature='reduce-T':
every 'nraise' steps the instantaneous temperature is
reduced by -delta_T (i.e. delta_t < 0 is added to T)
The instantaneous temperature is calculated at the end of
every ionic move and BEFORE rescaling. This is the temperature
reported in the main output.
For delta_t < 0, the actual average rate of heating or cooling
should be roughly C*delta_t/(nraise*dt) (C=1 for an
ideal gas, C=0.5 for a harmonic solid, theorem of energy
equipartition between all quadratic degrees of freedom).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nraise
Type: INTEGER
Default: 1
Description: if ion_temperature='reduce-T':
every 'nraise' steps the instantaneous temperature is
reduced by -delta_T (.e. delta_t is added to the temperature)
if ion_temperature='rescale-v':
every 'nraise' steps the average temperature, computed from
the last nraise steps, is rescaled to tempw
if ion_temperature='rescaling' and calculation='vc-md':
every 'nraise' steps the instantaneous temperature
is rescaled to tempw
if ion_temperature='berendsen':
the "rise time" parameter is given in units of the time step:
tau = nraise*dt, so dt/tau = 1/nraise
if ion_temperature='andersen':
the "collision frequency" parameter is given as nu=1/tau
defined above, so nu*dt = 1/nraise
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: refold_pos
Type: LOGICAL
Default: .FALSE.
Description: This keyword applies only in the case of molecular dynamics or
damped dynamics. If true the ions are refolded at each step into
the supercell.
+--------------------------------------------------------------------
\\\---
///---
KEYWORDS USED ONLY IN BFGS CALCULATIONS
+--------------------------------------------------------------------
Variable: upscale
Type: REAL
Default: 100.D0
Description: Max reduction factor for conv_thr during structural optimization
conv_thr is automatically reduced when the relaxation
approaches convergence so that forces are still accurate,
but conv_thr will not be reduced to less that
conv_thr / upscale.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: bfgs_ndim
Type: INTEGER
Default: 1
Description: Number of old forces and displacements vectors used in the
PULAY mixing of the residual vectors obtained on the basis
of the inverse hessian matrix given by the BFGS algorithm.
When bfgs_ndim = 1, the standard quasi-Newton BFGS method is
used.
(bfgs only)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: trust_radius_max
Type: REAL
Default: 0.8D0
Description: Maximum ionic displacement in the structural relaxation.
(bfgs only)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: trust_radius_min
Type: REAL
Default: 1.D-3
Description: Minimum ionic displacement in the structural relaxation
BFGS is reset when trust_radius < trust_radius_min.
(bfgs only)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: trust_radius_ini
Type: REAL
Default: 0.5D0
Description: Initial ionic displacement in the structural relaxation.
(bfgs only)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: w_1
Type: REAL
Default: 0.01D0
See: w_2
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: w_2
Type: REAL
Default: 0.5D0
Description: Parameters used in line search based on the Wolfe conditions.
(bfgs only)
+--------------------------------------------------------------------
\\\---
===END OF NAMELIST======================================================
========================================================================
NAMELIST: &CELL
INPUT THIS NAMELIST ONLY IF CALCULATION = 'VC-RELAX', 'VC-MD'
+--------------------------------------------------------------------
Variable: cell_dynamics
Type: CHARACTER
Description: Specify the type of dynamics for the cell.
For different type of calculation different possibilities
are allowed and different default values apply:
CASE ( calculation = 'vc-relax' )
'none': no dynamics
'sd': steepest descent ( not implemented )
'damp-pr': damped (Beeman) dynamics of the Parrinello-Rahman
extended lagrangian
'damp-w': damped (Beeman) dynamics of the new Wentzcovitch
extended lagrangian
'bfgs': BFGS quasi-newton algorithm (default)
ion_dynamics must be 'bfgs' too
CASE ( calculation = 'vc-md' )
'none': no dynamics
'pr': (Beeman) molecular dynamics of the Parrinello-Rahman
extended lagrangian
'w': (Beeman) molecular dynamics of the new Wentzcovitch
extended lagrangian
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: press
Type: REAL
Default: 0.D0
Description: Target pressure [KBar] in a variable-cell md or relaxation run.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: wmass
Type: REAL
Default: 0.75*Tot_Mass/pi**2 for Parrinello-Rahman MD;
0.75*Tot_Mass/pi**2/Omega**(2/3) for Wentzcovitch MD
Description: Fictitious cell mass [amu] for variable-cell simulations
(both 'vc-md' and 'vc-relax')
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: cell_factor
Type: REAL
Default: 1.2D0
Description: Used in the construction of the pseudopotential tables.
It should exceed the maximum linear contraction of the
cell during a simulation.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: press_conv_thr
Type: REAL
Default: 0.5D0 Kbar
Description: Convergence threshold on the pressure for variable cell
relaxation ('vc-relax' : note that the other convergence
thresholds for ionic relaxation apply as well).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: cell_dofree
Type: CHARACTER
Default: 'all'
Description: Select which of the cell parameters should be moved:
all = all axis and angles are moved
x = only the x component of axis 1 (v1_x) is moved
y = only the y component of axis 2 (v2_y) is moved
z = only the z component of axis 3 (v3_z) is moved
xy = only v1_x and v2_y are moved
xz = only v1_x and v3_z are moved
yz = only v2_y and v3_z are moved
xyz = only v1_x, v2_y, v3_z are moved
shape = all axis and angles, keeping the volume fixed
volume = the volume changes, keeping all angles fixed (i.e. only celldm(1) changes)
2Dxy = only x and y components are allowed to change
2Dshape = as above, keeping the area in xy plane fixed
BEWARE: if axis are not orthogonal, some of these options do not
work (symmetry is broken). If you are not happy with them,
edit subroutine init_dofree in file Modules/cell_base.f90
+--------------------------------------------------------------------
===END OF NAMELIST======================================================
========================================================================
CARD: ATOMIC_SPECIES
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
ATOMIC_SPECIES
X(1) Mass_X(1) PseudoPot_X(1)
X(2) Mass_X(2) PseudoPot_X(2)
. . .
X(ntyp) Mass_X(ntyp) PseudoPot_X(ntyp)
/////////////////////////////////////////
DESCRIPTION OF ITEMS:
+--------------------------------------------------------------------
Variable: X
Type: CHARACTER
Description: label of the atom. Acceptable syntax:
chemical symbol X (1 or 2 characters, case-insensitive)
or chemical symbol plus a number or a letter, as in
"Xn" (e.g. Fe1) or "X_*" or "X-*" (e.g. C1, C_h;
max total length cannot exceed 3 characters)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: Mass_X
Type: REAL
Description: mass of the atomic species [amu: mass of C = 12]
Used only when performing Molecular Dynamics run
or structural optimization runs using Damped MD.
Not actually used in all other cases (but stored
in data files, so phonon calculations will use
these values unless other values are provided)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: PseudoPot_X
Type: CHARACTER
Description: File containing PP for this species.
The pseudopotential file is assumed to be in the new UPF format.
If it doesn't work, the pseudopotential format is determined by
the file name:
*.vdb or *.van Vanderbilt US pseudopotential code
*.RRKJ3 Andrea Dal Corso's code (old format)
none of the above old PWscf norm-conserving format
+--------------------------------------------------------------------
===END OF CARD==========================================================
========================================================================
CARD: ATOMIC_POSITIONS { alat | bohr | angstrom | crystal | crystal_sg }
________________________________________________________________________
* IF calculation == 'bands' OR calculation == 'nscf' :
Specified atomic positions will be IGNORED and those from the
previous scf calculation will be used instead !!!
* ELSE IF :
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
ATOMIC_POSITIONS { alat | bohr | angstrom | crystal | crystal_sg }
X(1) x(1) y(1) z(1) { if_pos(1)(1) if_pos(2)(1) if_pos(3)(1) }
X(2) x(2) y(2) z(2) { if_pos(1)(2) if_pos(2)(2) if_pos(3)(2) }
. . .
X(nat) x(nat) y(nat) z(nat) { if_pos(1)(nat) if_pos(2)(nat) if_pos(3)(nat) }
/////////////////////////////////////////
ENDIF
________________________________________________________________________
DESCRIPTION OF ITEMS:
+--------------------------------------------------------------------
Card's flags: { alat | bohr | angstrom | crystal | crystal_sg }
Default: (DEPRECATED) alat
Description: alat : atomic positions are in cartesian coordinates, in
units of the lattice parameter (either celldm(1)
or A). If no option is specified, 'alat' is assumed;
not specifying units is DEPRECATED and will no
longer be allowed in the future
bohr : atomic positions are in cartesian coordinate,
in atomic units (i.e. Bohr radii)
angstrom: atomic positions are in cartesian coordinates,
in Angstrom
crystal : atomic positions are in crystal coordinates, i.e.
in relative coordinates of the primitive lattice
vectors as defined either in card CELL_PARAMETERS
or via the ibrav + celldm / a,b,c... variables
crystal_sg : atomic positions are in crystal coordinates, i.e.
in relative coordinates of the primitive lattice.
This option differs from the previous one because
in this case only the symmetry inequivalent atoms
are given. The variable space_group must indicate
the space group number used to find the symmetry
equivalent atoms. The other variables that control
this option are uniqueb, origin_choice, and
rhombohedral.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: X
Type: CHARACTER
Description: label of the atom as specified in ATOMIC_SPECIES
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: x, y, z
Type: REAL
Description: atomic positions
NOTE: each atomic coordinate can also be specified as a simple algebraic expression.
To be interpreted correctly expression must NOT contain any blank
space and must NOT start with a "+" sign. The available expressions are:
+ (plus), - (minus), / (division), * (multiplication), ^ (power)
All numerical constants included are considered as double-precision numbers;
i.e. 1/2 is 0.5, not zero. Other functions, such as sin, sqrt or exp are
not available, although sqrt can be replaced with ^(1/2).
Example:
C 1/3 1/2*3^(-1/2) 0
is equivalent to
C 0.333333 0.288675 0.000000
Please note that this feature is NOT supported by XCrysDen (which will
display a wrong structure, or nothing at all).
When atomic positions are of type crystal_sg coordinates can be given
in the following three forms (Wyckoff positions):
C 1a
C 8g x
C 24m x y
The first form must be used when the Wyckoff letter determines uniquely
all three coordinates, the second form when the Wyckoff letter
and one coordinate are needed, the third form when one letter and two
coordinates are needed.
The forms:
C 8g x x x
C 24m x x y
are not allowed, but
C x x x
C x x y
are correct.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: if_pos(1), if_pos(2), if_pos(3)
Type: INTEGER
Default: 1
Description: component i of the force for this atom is multiplied by if_pos(i),
which must be either 0 or 1. Used to keep selected atoms and/or
selected components fixed in MD dynamics or
structural optimization run.
With crystal_sg atomic coordinates the constraints are copied in all equivalent
atoms.
+--------------------------------------------------------------------
===END OF CARD==========================================================
========================================================================
CARD: K_POINTS { tpiba | automatic | crystal | gamma | tpiba_b | crystal_b | tpiba_c | crystal_c }
________________________________________________________________________
* IF tpiba OR crystal OR tpiba_b OR crystal_b OR tpiba_c OR crystal_c :
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
K_POINTS tpiba | crystal | tpiba_b | crystal_b | tpiba_c | crystal_c
nks
xk_x(1) xk_y(1) xk_z(1) wk(1)
xk_x(2) xk_y(2) xk_z(2) wk(2)
. . .
xk_x(nks) xk_y(nks) xk_z(nks) wk(nks)
/////////////////////////////////////////
* ELSE IF automatic :
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
K_POINTS automatic
nk1 nk2 nk3 sk1 sk2 sk3
/////////////////////////////////////////
* ELSE IF gamma :
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
K_POINTS gamma
/////////////////////////////////////////
ENDIF
________________________________________________________________________
DESCRIPTION OF ITEMS:
+--------------------------------------------------------------------
Card's flags: { tpiba | automatic | crystal | gamma | tpiba_b | crystal_b | tpiba_c | crystal_c }
Default: tbipa
Description: tpiba : read k-points in cartesian coordinates,
in units of 2 pi/a (default)
automatic: automatically generated uniform grid of k-points, i.e,
generates ( nk1, nk2, nk3 ) grid with ( sk1, sk2, sk3 ) offset.
nk1, nk2, nk3 as in Monkhorst-Pack grids
k1, k2, k3 must be 0 ( no offset ) or 1 ( grid displaced
by half a grid step in the corresponding direction )
BEWARE: only grids having the full symmetry of the crystal
work with tetrahedra. Some grids with offset may not work.
crystal : read k-points in crystal coordinates, i.e. in relative
coordinates of the reciprocal lattice vectors
gamma : use k = 0 (no need to list k-point specifications after card)
In this case wavefunctions can be chosen as real,
and specialized subroutines optimized for calculations
at the gamma point are used (memory and cpu requirements
are reduced by approximately one half).
tpiba_b : Used for band-structure plots.
k-points are in units of 2 pi/a.
nks points specify nks-1 lines in reciprocal space.
Every couple of points identifies the initial and
final point of a line. pw.x generates N
intermediate points of the line where N is the
weight of the first point.
crystal_b: as tpiba_b, but k-points are in crystal coordinates.
tpiba_c : Used for band-structure contour plots.
k-points are in units of 2 pi/a. nks must be 3.
3 k-points k_0, k_1, and k_2 specify a rectangle
in reciprocal space of vertices k_0, k_1, k_2,
k_1 + k_2 - k_0: k_0 + \alpha (k_1-k_0)+
\beta (k_2-k_0) with 0<\alpha,\beta < 1.
The code produces a uniform mesh n1 x n2
k points in this rectangle. n1 and n2 are
the weights of k_1 and k_2. The weight of k_0
is not used.
crystal_c: as tpiba_c, but k-points are in crystal coordinates.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: nks
Type: INTEGER
Description: Number of supplied special k-points.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: xk_x, xk_y, xk_z, wk
Type: REAL
Description: Special k-points (xk_x/y/z) in the irreducible Brillouin Zone
(IBZ) of the lattice (with all symmetries) and weights (wk)
See the literature for lists of special points and
the corresponding weights.
If the symmetry is lower than the full symmetry
of the lattice, additional points with appropriate
weights are generated. Notice that such procedure
assumes that ONLY k-points in the IBZ are provided in input
In a non-scf calculation, weights do not affect the results.
If you just need eigenvalues and eigenvectors (for instance,
for a band-structure plot), weights can be set to any value
(for instance all equal to 1).
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: nk1, nk2, nk3
Type: INTEGER
Description: These parameters specify the k-point grid
(nk1 x nk2 x nk3) as in Monkhorst-Pack grids.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: sk1, sk2, sk3
Type: INTEGER
Description: The grid offsets; sk1, sk2, sk3 must be
0 ( no offset ) or 1 ( grid displaced by
half a grid step in the corresponding direction ).
+--------------------------------------------------------------------
===END OF CARD==========================================================
========================================================================
CARD: CELL_PARAMETERS { alat | bohr | angstrom }
OPTIONAL CARD, NEEDED ONLY IF IBRAV = 0 IS SPECIFIED, IGNORED OTHERWISE !
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
CELL_PARAMETERS { alat | bohr | angstrom }
v1(1) v1(2) v1(3)
v2(1) v2(2) v2(3)
v3(1) v3(2) v3(3)
/////////////////////////////////////////
DESCRIPTION OF ITEMS:
+--------------------------------------------------------------------
Card's flags: { alat | bohr | angstrom }
Description: 'bohr'/'angstrom': lattice vectors in bohr radii / angstrom.
In this case the lattice parameter alat = sqrt(v1*v1).
'alat' / nothing specified: lattice vectors in units of the
lattice parameter (either celldm(1) or a). Not specifying
units is DEPRECATED and will not be allowed in the future.
If nothing specified and no lattice parameter specified,
'bohr' is assumed - DEPRECATED, will no longer be allowed
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: v1, v2, v3
Type: REAL
Description: Crystal lattice vectors (in cartesian axis):
v1(1) v1(2) v1(3) ... 1st lattice vector
v2(1) v2(2) v2(3) ... 2nd lattice vector
v3(1) v3(2) v3(3) ... 3rd lattice vector
+--------------------------------------------------------------------
===END OF CARD==========================================================
========================================================================
CARD: CONSTRAINTS
OPTIONAL CARD, USED FOR CONSTRAINED DYNAMICS OR CONSTRAINED OPTIMISATIONS
(ONLY IF ION_DYNAMICS='DAMP' OR 'VERLET', VARIABLE-CELL EXCEPTED)
When this card is present the SHAKE algorithm is automatically used.
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
CONSTRAINTS
nconstr { constr_tol }
constr_type(1) constr(1)(1) constr(2)(1) [ constr(3)(1) constr(4)(1) ] { constr_target(1) }
constr_type(2) constr(1)(2) constr(2)(2) [ constr(3)(2) constr(4)(2) ] { constr_target(2) }
. . .
constr_type(nconstr) constr(1)(nconstr) constr(2)(nconstr) [ constr(3)(nconstr) constr(4)(nconstr) ] { constr_target(nconstr) }
/////////////////////////////////////////
DESCRIPTION OF ITEMS:
+--------------------------------------------------------------------
Variable: nconstr
Type: INTEGER
Description: Number of constraints.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: constr_tol
Type: REAL
Description: Tolerance for keeping the constraints satisfied.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: constr_type
Type: CHARACTER
Description: Type of constrain :
'type_coord' : constraint on global coordination-number, i.e. the
average number of atoms of type B surrounding the
atoms of type A. The coordination is defined by
using a Fermi-Dirac.
(four indexes must be specified).
'atom_coord' : constraint on local coordination-number, i.e. the
average number of atoms of type A surrounding a
specific atom. The coordination is defined by
using a Fermi-Dirac.
(four indexes must be specified).
'distance' : constraint on interatomic distance
(two atom indexes must be specified).
'planar_angle' : constraint on planar angle
(three atom indexes must be specified).
'torsional_angle' : constraint on torsional angle
(four atom indexes must be specified).
'bennett_proj' : constraint on the projection onto a given direction
of the vector defined by the position of one atom
minus the center of mass of the others.
G.Roma,J.P.Crocombette: J.Nucl.Mater.403,32(2010)
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: constr(1), constr(2), constr(3), constr(4)
Description: These variables have different meanings
for different constraint types:
'type_coord' : constr(1) is the first index of the
atomic type involved
constr(2) is the second index of the
atomic type involved
constr(3) is the cut-off radius for
estimating the coordination
constr(4) is a smoothing parameter
'atom_coord' : constr(1) is the atom index of the
atom with constrained coordination
constr(2) is the index of the atomic
type involved in the coordination
constr(3) is the cut-off radius for
estimating the coordination
constr(4) is a smoothing parameter
'distance' : atoms indices object of the
constraint, as they appear in
the 'ATOMIC_POSITION' CARD
'planar_angle', 'torsional_angle' : atoms indices object of the
constraint, as they appear in the
'ATOMIC_POSITION' CARD (beware the
order)
'bennett_proj' : constr(1) is the index of the atom
whose position is constrained.
constr(2:4) are the three coordinates
of the vector that specifies the
constraint direction.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: constr_target
Type: REAL
Description: Target for the constrain ( angles are specified in degrees ).
This variable is optional.
+--------------------------------------------------------------------
===END OF CARD==========================================================
========================================================================
CARD: OCCUPATIONS
OPTIONAL CARD, USED ONLY IF OCCUPATIONS = 'FROM_INPUT', IGNORED OTHERWISE !
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
OCCUPATIONS
f_inp1(1) f_inp1(2) . . . f_inp1(nbnd)
[ f_inp2(1) f_inp2(2) . . . f_inp2(nbnd) ]
/////////////////////////////////////////
DESCRIPTION OF ITEMS:
+--------------------------------------------------------------------
Variable: f_inp1
Type: REAL
Description: Occupations of individual states (MAX 10 PER ROW).
For spin-polarized calculations, these are majority spin states.
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variable: f_inp2
Type: REAL
Description: Occupations of minority spin states (MAX 10 PER ROW)
To be specified only for spin-polarized calculations.
+--------------------------------------------------------------------
===END OF CARD==========================================================
========================================================================
CARD: ATOMIC_FORCES
OPTIONAL CARD USED TO SPECIFY EXTERNAL FORCES ACTING ON ATOMS.
BEWARE: IF THE SUM OF EXTERNAL FORCES IS NOT ZERO, THE CENTER
OF MASS OF THE SYSTEM WILL MOVE
/////////////////////////////////////////
// Syntax: //
/////////////////////////////////////////
ATOMIC_FORCES
X(1) fx(1) fy(1) fz(1)
X(2) fx(2) fy(2) fz(2)
. . .
X(nat) fx(nat) fy(nat) fz(nat)
/////////////////////////////////////////
DESCRIPTION OF ITEMS:
+--------------------------------------------------------------------
Variable: X
Type: CHARACTER
Description: label of the atom as specified in ATOMIC_SPECIES
+--------------------------------------------------------------------
+--------------------------------------------------------------------
Variables: fx, fy, fz
Type: REAL
Description: external force on atom X (cartesian components, Ry/a.u. units)
+--------------------------------------------------------------------
===END OF CARD==========================================================