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### angle_style quartic command

Syntax:

    angle_style quartic

Examples:

    angle_style quartic
    angle_coeff 1 129.1948 56.8726 -25.9442 -14.2221

Description:

The quartic angle style uses the potential

where theta0 is the equilibrium value of the angle, and K is a prefactor. Note that the usual 1/2 factor is included in K.

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:

- theta0 (degrees)
- K2 (energy/radian^2)
- K3 (energy/radian^3)
- K4 (energy/radian^4)

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_MISC package. See the Making LAMMPS section for more info on packages.

Related commands:

angle_coeff

Default: none