Syntax:
dihedral_style style
Examples:
dihedral_style harmonic dihedral_style multi/harmonic dihedral_style hybrid harmonic charmm
Description:
Set the formula(s) LAMMPS uses to compute dihedral interactions between quadruplets of atoms, which remain in force for the duration of the simulation. The list of dihedral quadruplets is read in by a read_data or read_restart command from a data or restart file.
Hybrid models where dihedrals are computed using different dihedral potentials can be setup using the hybrid dihedral style.
The coefficients associated with a dihedral style can be specified in a data or restart file or via the dihedral_coeff command.
In the formulas listed for each dihedral style, phi is the torsional angle defined by the quadruplet of atoms.
Note that when both a dihedral 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 are some important points to take note of when defining the LAMMPS dihedral coefficients in the formulas that follow so that they are compatible with other force fields:
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:
Dihedral styles can only be set for atom styles that allow dihedrals to be defined.
Dihedral 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:
Default:
dihedral_style none