Syntax:
dihedral_coeff N args
Examples:
dihedral_coeff 1 80.0 1 3 dihedral_coeff * 80.0 1 3 0.5 dihedral_coeff 2* 80.0 1 3 0.5
Description:
Specify the dihedral force field coefficients for one or more dihedral types. The number and meaning of the coefficients depends on the dihedral style. Dihedral 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 dihedral types. This takes the form "*" or "*n" or "n*" or "m*n". If N = the number of dihedral 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).
Note that using a dihedral_coeff command can override a previous setting for the same dihedral type. For example, these commands set the coeffs for all dihedral types, then overwrite the coeffs for just dihedral type 2:
dihedral_coeff * 80.0 1 3 dihedral_coeff 2 200.0 1 3
A line in a data file that specifies dihedral coefficients uses the exact same format as the arguments of the dihedral_coeff command in an input script, except that wild-card asteriks should not be used since coefficients for all N types must be listed in the file. For example, under the "Dihedral Coeffs" section of a data file, the line that corresponds to the 1st example above would be listed as
1 80.0 1 3
Here is an alphabetic list of dihedral styles defined in LAMMPS. Click on the style to display the formula it computes and coefficients specified by the associated dihedral_coeff command:
Restrictions:
This command must come after the simulation box is defined by a read_data, read_restart, or create_box command.
An dihedral style must be defined before any dihedral coefficients are set, either in the input script or in a data file.
Related commands:
Default: none