forked from lijiext/lammps
97 lines
2.5 KiB
Plaintext
97 lines
2.5 KiB
Plaintext
.. index:: angle_style harmonic
|
|
|
|
angle_style harmonic command
|
|
============================
|
|
|
|
angle_style harmonic/intel command
|
|
==================================
|
|
|
|
angle_style harmonic/kk command
|
|
===============================
|
|
|
|
angle_style harmonic/omp command
|
|
================================
|
|
|
|
Syntax
|
|
""""""
|
|
|
|
.. parsed-literal::
|
|
|
|
angle_style harmonic
|
|
|
|
Examples
|
|
""""""""
|
|
|
|
.. parsed-literal::
|
|
|
|
angle_style harmonic
|
|
angle_coeff 1 300.0 107.0
|
|
|
|
Description
|
|
"""""""""""
|
|
|
|
The *harmonic* angle style uses the potential
|
|
|
|
.. image:: Eqs/angle_harmonic.jpg
|
|
:align: center
|
|
|
|
where theta0 is the equilibrium value of the angle, and K is a
|
|
prefactor. Note that the usual 1/2 factor is included in K.
|
|
|
|
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:
|
|
|
|
* K (energy/radian^2)
|
|
* theta0 (degrees)
|
|
|
|
Theta0 is specified in degrees, but LAMMPS converts it to radians
|
|
internally; hence the units of K are in energy/radian^2.
|
|
|
|
|
|
----------
|
|
|
|
|
|
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 in :doc:`Section_accelerate <Section_accelerate>`
|
|
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 GPU, USER-INTEL, KOKKOS,
|
|
USER-OMP and OPT packages, respectively. They are only enabled if
|
|
LAMMPS was built with those packages. See the :ref:`Making LAMMPS <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 :ref:`-suffix command-line switch <start_7>` when you invoke LAMMPS, or you can
|
|
use the :doc:`suffix <suffix>` command in your input script.
|
|
|
|
See :doc:`Section_accelerate <Section_accelerate>` of the manual for
|
|
more instructions on how to use the accelerated styles effectively.
|
|
|
|
|
|
----------
|
|
|
|
|
|
Restrictions
|
|
""""""""""""
|
|
none
|
|
|
|
This angle style can only be used if LAMMPS was built with the
|
|
MOLECULE package (which it is by default). See the :ref:`Making LAMMPS <start_3>` section for more info on packages.
|
|
|
|
Related commands
|
|
""""""""""""""""
|
|
|
|
:doc:`angle_coeff <angle_coeff>`
|
|
|
|
**Default:** none
|
|
|
|
|
|
.. _lws: http://lammps.sandia.gov
|
|
.. _ld: Manual.html
|
|
.. _lc: Section_commands.html#comm
|