angle_style mm3 command

Syntax

angle_style mm3

Examples

angle_style mm3
angle_coeff 1 100.0 107.0

Description

The mm3 angle style uses the potential that is anharmonic in the angle as defined in (Allinger)

_images/angle_mm3.jpg

where theta0 is the equilibrium value of the angle, and K is a prefactor. The anharmonic prefactors have units deg^(-n), for example -0.014 deg^(-1), 5.6(10)^(-5) deg^(-2), …

The following coefficients must be defined for each angle type via the angle_coeff command as in the example above, or in the data file or restart files read by the read_data or read_restart commands:

  • K (energy/radian^2)
  • theta0 (degrees)

Theta0 is specified in degrees, but LAMMPS converts it to radians internally; hence the units of K are in energy/radian^2.

Restrictions

This angle style can only be used if LAMMPS was built with the USER_YAFF package. See the Build package doc page for more info.