"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)

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angle_style cosine/buck6d command :h3

[Syntax:]

angle_style cosine/buck6d :pre

[Examples:]

angle_style cosine/buck6d
angle_coeff 1  cosine/buck6d  1.978350  4  180.000000 :pre

[Description:]

The {cosine/buck6d} angle style uses the potential

:c,image(Eqs/angle_cosine_buck6d.jpg)

where K is the energy constant, n is the periodic multiplicity and 
Theta0 is the equilibrium angle.

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

K (energy)
n 
Theta0 (degrees) :ul

Theta0 is specified in degrees, but LAMMPS converts it to radians 
internally.

Additional to the cosine term the {cosine/buck6d} angle style computes 
the short range (vdW) interaction belonging to the 
"pair_buck6d"_pair_buck6d_coul_gauss.html between the end atoms of 
the angle.  For this reason this angle style only works in combination
with the "pair_buck6d"_pair_buck6d_coul_gauss.html styles and needs
the "special_bonds"_special_bonds.html 1-3 interactions to be weighted
0.0 to prevent double counting.

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[Restrictions:]

{cosine/buck6d} can only be used in combination with the
"pair_buck6d"_pair_buck6d_coul_gauss.html style and with a 
"special_bonds"_special_bonds.html 0.0 weighting of 1-3 interactions.  

This angle style can only be used if LAMMPS was built with the
USER-MOFFF package.  See the "Making
LAMMPS"_Section_start.html#start_3 section for more info on packages.

[Related commands:]

"angle_coeff"_angle_coeff.html

[Default:] none
