"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)

:line

angle_style cg/cmm command :h3

[Syntax:]

angle_style cg/cmm :pre

[Examples:]

angle_style cg/cmm
angle_coeff 1 300.0 107.0 lj9_6 0.4491 3.7130 :pre

[Description:]

The {cg/cmm} angle style is a combination of the harmonic angle potential,

:c,image(Eqs/angle_harmonic.jpg)

where theta0 is the equilibrium value of the angle and K a prefactor,
with the {repulsive} part of the non-bonded {cg/cmm} pair style
between the atoms 1 and 3.  This angle potential is intended for
coarse grained MD simulations with the CMM parametrization using the
"pair_style cg/cmm"_pair_cmm.html.  Relative to the pair_style
{cg/cmm}, however, the energy is shifted by {epsilon}, to avoid sudden
jumps.  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"_angle_coeff.html command as in the example above. As
with other CMM coarse grained parameters, they cannot be set in the
data file, but can be restored from restarts via the
"read_restart"_read_restart.html command:

K (energy/radian^2)
theta0 (degrees)
cg_type (string, one of lj9_6, lj12_4, lj12_6)
epsilon (energy units)
sigma (distance units) :ul

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-cg-cmm" package.  See the "Making LAMMPS"_Section_start.html#2_3 section 
for more info on packages.

[Related commands:]

"angle_coeff"_angle_coeff.html, "angle_style
harmonic"_angle_harmonic.html, "pair_style cg/cmm"_pair_cmm.html

[Default:] none
