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Update docs: angle_cross

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Richard Berger
2019-11-14 17:02:23 -05:00
parent 579b1271b0
commit 35f305eac4
4 changed files with 19 additions and 98 deletions
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doc/src/Eqs/angle_cross.tex
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\documentclass[12pt]{article}
\begin{document}
\thispagestyle{empty}
$$
E = K_{SS} \left(r_{12}-r_{12,0}\right)\left(r_{32}-r_{32,0}\right) + K_{BS0}\left(r_{12}-r_{12,0}\right)\left(\theta-\theta_0\right) + K_{BS1}\left(r_{32}-r_{32,0}\right)\left(\theta-\theta_0\right)
$$
\end{document}

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doc/src/angle_cross.rst
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@ -1,13 +1,13 @@
.. index:: angle\_style cross
.. index:: angle_style cross
angle\_style cross command
angle_style cross command
==========================
Syntax
""""""
.. parsed-literal::
.. code-block:: LAMMPS
angle_style cross
@ -15,7 +15,7 @@ Examples
""""""""
.. parsed-literal::
.. code-block:: LAMMPS
angle_style cross
angle_coeff 1 200.0 100.0 100.0 1.25 1.25 107.0
@ -26,13 +26,14 @@ Description
The *cross* angle style uses a potential that couples the bond stretches of
a bend with the angle stretch of that bend:
.. image:: Eqs/angle_cross.jpg
:align: center
.. math::
where r12,0 is the rest value of the bond length between atom 1 and 2,
r32,0 is the rest value of the bond length between atom 2 and 2,
and theta0 is the rest value of the angle. KSS is the force constant of
the bond stretch-bond stretch term and KBS0 and KBS1 are the force constants
E = K_{SS} \left(r_{12}-r_{12,0}\right)\left(r_{32}-r_{32,0}\right) + K_{BS0}\left(r_{12}-r_{12,0}\right)\left(\theta-\theta_0\right) + K_{BS1}\left(r_{32}-r_{32,0}\right)\left(\theta-\theta_0\right)
where :math:`r_{12,0}` is the rest value of the bond length between atom 1 and 2,
:math:`r_{32,0}` is the rest value of the bond length between atom 3 and 2,
and :math:`\theta_0` is the rest value of the angle. :math:`K_{SS}` is the force constant of
the bond stretch-bond stretch term and :math:`K_{BS0}` and :math:`K_{BS1}` are the force constants
of the bond stretch-angle stretch terms.
The following coefficients must be defined for each angle type via the
@ -40,15 +41,15 @@ The following coefficients must be defined for each angle type via the
the data file or restart files read by the :doc:`read\_data <read_data>`
or :doc:`read\_restart <read_restart>` commands:
* KSS (energy/distance\^2)
* KBS0 (energy/distance/rad)
* KBS1 (energy/distance/rad)
* r12,0 (distance)
* r32,0 (distance)
* theta0 (degrees)
* :math:`K_{SS}` (energy/distance\^2)
* :math:`K_{BS0}` (energy/distance/rad)
* :math:`K_{BS1}` (energy/distance/rad)
* :math:`r_{12,0}` (distance)
* :math:`r_{32,0}` (distance)
* :math:`\theta_0` (degrees)
Theta0 is specified in degrees, but LAMMPS converts it to radians
internally; hence the units of KBS0 and KBS1 are in energy/distance/radian.
:math:`\theta_0` is specified in degrees, but LAMMPS converts it to radians
internally; hence the units of :math:`K_{BS0}` and :math:`K_{BS1}` are in energy/distance/radian.
Restrictions
""""""""""""
@ -64,12 +65,3 @@ Related commands
:doc:`angle\_coeff <angle_coeff>`
**Default:** none
----------
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Commands_all.html