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improper_style command

Syntax:

improper_style style 

Examples:

improper_style harmonic
improper_style cvff
improper_style hybrid cvff harmonic 

Description:

Set the formula(s) LAMMPS uses to compute improper interactions between quadruplets of atoms, which remain in force for the duration of the simulation. The list of improper quadruplets is read in by a read_data or read_restart command from a data or restart file.

Hybrid models where impropers are computed using different improper potentials can be setup using the hybrid improper style.

The coefficients associated with a improper style can be specified in a data or restart file or via the improper_coeff command.

Note that when both an improper and pair style is defined, the special_bond command often needs to be used to turn off (or weight) the pairwise interactions that would otherwise exist between the 4 bonded atoms.


Here is an alphabetic list of improper styles defined in LAMMPS. Click on the style to display the formula it computes and coefficients specified by the associated improper_coeff command:


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 or other packages as noted in their documentation. They are only enabled if LAMMPS was built with that package. See the Making LAMMPS section for more info.

Related commands:

improper_coeff

Default:

improper_style none