Syntax:
improper_style style
Examples:
improper_style harmonic improper_style cvff
Description:
Set the formula LAMMPS will use to compute improper interactions for quadruplets (trigonal centers) of atoms. The list of atom quadruplets are specified in the data or restart file and are read in by a read_data or read_restart command. The coefficients for the formula for each improper type can also be specified in those files or by the improper_coeff command.
A style of none means improper forces are not computed, even if impropers are defined.
The harmonic style uses the potential
where X is the improper angle, X0 is its equilibrium value, and K is a prefactor. K and X0 are coefficients defined for each improper type.
The cvff style uses the potential
where phi is the Wilson out-of-plane angle. K, d, and n are coefficients defined for each improper type.
Restrictions:
Improper styles can only be set for atom_style choices that allow impropers to be defined.
Improper styles are part of the "molecular" package. They are only enabled if LAMMPS was built with that package. See the Making LAMMPS section for more info.
Related commands:
Default:
improper_style none