lammps/doc/angle_cosine_shift.txt

"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/shift command :h3
angle_style cosine/shift/omp command :h3

[Syntax:]

angle_style cosine/shift :pre

[Examples:]

angle_style cosine/shift
angle_coeff * 10.0 45.0 :pre

[Description:]

The {cosine/shift} angle style uses the potential

:c,image(Eqs/angle_cosine_shift.jpg)

where theta0 is the equilibrium angle. The potential is bounded
between -Umin and zero. In the neighborhood of the minimum E=- Umin +
Umin/4(theta-theta0)^2 hence the spring constant is umin/2.

The following 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:

umin (energy)
theta (angle) :ul

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Styles with a {cuda}, {gpu}, {omp}, or {opt} suffix are functionally 
the same as the corresponding style without the suffix.  They have 
been optimized to run faster, depending on your available hardware, 
as discussed in "this section"_Section_accelerate.html of the manual.
The accelerated styles take the same arguments and should produce the
same results, except for round-off and precision issues.

These accelerated styles are part of the USER-CUDA, GPU, USER-OMP and OPT
packages, respectively.  They are only enabled if LAMMPS was built with
those packages.  See the "Making LAMMPS"_Section_start.html#start_3
section for more info.

You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the "-suffix command-line
switch"_Section_start.html#start_6 when you invoke LAMMPS, or you can
use the "suffix"_suffix.html command in your input script.

See "this section"_Section_accelerate.html of the manual for more
instructions on how to use the accelerated styles effectively.

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[Restrictions:]

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

[Related commands:]

"angle_coeff"_angle_coeff.html,
"angle_cosineshiftexp"_angle_cosineshiftexp.html

[Default:] none