Syntax:
improper_coeff N args
Examples:
improper_coeff 1 300.0 0.0 improper_coeff * 80.2 -1 2 improper_coeff *4 80.2 -1 2
Description:
Specify the force field coefficients for one or more improper types. The number and meaning of the coefficients depends on the improper style. Improper coefficients can also be set in the data file read by the read_data command or in a restart file.
N can be specified in one of two ways. An explicit numeric value can be used, as in the 1st example above. Or a wild-card asterik can be used to set the coefficients for multiple improper types. This takes the form "*" or "*n" or "n*" or "m*n". If N = the number of improper types, then an asterik with no numeric values means all types from 1 to N. A leading asterik means all types from 1 to n (inclusive). A trailing asterik means all types from n to N (inclusive). A middle asterik means all types from m to n (inclusive).
A line in a data file that specifies improper coefficients uses the exact same format as the arguments of the improper_coeff command in an input script, except that no wild-card asterik can be used. For example, under the "Improper Coeffs" section of a data file, the line that corresponds to the 1st example above would be listed as
1 300.0 0.0
See the improper_style command for the formulas that use these coefficients. The units of each coefficient are shown in parenthesis.
For style harmonic, specify 2 coefficients:
For style cvff, specify 3 coefficients:
Restrictions:
This command must come after the simulation box is defined by a read_data, read_restart, or create_box command.
An improper style must be defined before any improper coefficients are set, either in the input script or in a data file.
Related commands:
Default: none