Update docs: angle_cosine_shift

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Richard Berger
2019-11-14 16:19:06 -05:00
parent c4511cb2fc
commit de166a3d16
4 changed files with 17 additions and 101 deletions

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\documentstyle[12pt]{article}
\begin{document}
$$
E=-\frac{Umin}{2} \left[ 1+Cos(\theta-\theta_0) \right]
$$
\end{document}

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.. index:: angle\_style cosine/shift
.. index:: angle_style cosine/shift
angle\_style cosine/shift command
angle_style cosine/shift command
=================================
angle\_style cosine/shift/omp command
=====================================
angle_style cosine/shift/omp command
====================================
Syntax
""""""
.. parsed-literal::
.. code-block:: LAMMPS
angle_style cosine/shift
@ -18,30 +18,33 @@ Examples
""""""""
.. parsed-literal::
.. code-block:: LAMMPS
angle_style cosine/shift
angle_coeff \* 10.0 45.0
angle_coeff * 10.0 45.0
Description
"""""""""""
The *cosine/shift* angle style uses the potential
.. image:: Eqs/angle_cosine_shift.jpg
:align: center
.. math::
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.
E = -\frac{U_{\text{min}}}{2} \left[ 1 + \cos(\theta-\theta_0) \right]
where :math:`\theta_0` is the equilibrium angle. The potential is bounded
between :math:`-U_{\text{min}}` and zero. In the neighborhood of the minimum
:math:`E = - U_{\text{min}} + U_{\text{min}}/4(\theta - \theta_0)^2` hence
the spring constant is :math:`\frac{U_{\text{min}}}{2}`.
The following coefficients must be defined for each angle type via the
:doc:`angle\_coeff <angle_coeff>` command as in the example above, or in
the data file or restart files read by the :doc:`read\_data <read_data>`
or :doc:`read\_restart <read_restart>` commands:
* umin (energy)
* theta (angle)
* :math:`U_{\text{min}}` (energy)
* :math:`\theta` (angle)
----------
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:doc:`angle\_cosine\_shift\_exp <angle_cosine_shift_exp>`
**Default:** none
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Commands_all.html

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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Commands_all.html)
:line
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
:line
Styles with a {gpu}, {intel}, {kk}, {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 on the "Speed packages"_Speed_packages.html doc
page. 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 GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively. They are only enabled if
LAMMPS was built with those packages. See the "Build
package"_Build_package.html doc page 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"_Run_options.html when you invoke LAMMPS, or you can use the
"suffix"_suffix.html command in your input script.
See the "Speed packages"_Speed_packages.html doc page for more
instructions on how to use the accelerated styles effectively.
:line
[Restrictions:]
This angle style can only be used if LAMMPS was built with the
USER-MISC package.
[Related commands:]
"angle_coeff"_angle_coeff.html,
"angle_cosine_shift_exp"_angle_cosine_shift_exp.html
[Default:] none