66 lines
1.5 KiB
ReStructuredText
66 lines
1.5 KiB
ReStructuredText
.. index:: improper\_style distharm
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improper\_style distharm command
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================================
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Syntax
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""""""
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improper\_style distharm
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Examples
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""""""""
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.. parsed-literal::
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improper_style distharm
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improper_coeff 1 25.0 0.5
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Description
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"""""""""""
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The *distharm* improper style uses the potential
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.. image:: Eqs/improper_distharm.jpg
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:align: center
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where d is the oriented distance between the central atom and the plane formed
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by the other three atoms. If the 4 atoms in an improper quadruplet
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(listed in the data file read by the :doc:`read\_data <read_data>`
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command) are ordered I,J,K,L then the L-atom is assumed to be the
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central atom. Note that this is different from the convention used
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in the improper\_style distance. The distance d is oriented and can take
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on negative values. This may lead to unwanted behavior if d0 is not equal to zero.
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The following coefficients must be defined for each improper type via
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the improper\_coeff command as in the example above, or in the data
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file or restart files read by the read\_data or read\_restart commands:
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* K (energy/distance\^2)
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* d0 (distance)
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----------
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Restrictions
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""""""""""""
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This improper style can only be used if LAMMPS was built with the
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USER-YAFF package. See the :doc:`Build package <Build_package>` doc
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page for more info.
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Related commands
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""""""""""""""""
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:doc:`improper\_coeff <improper_coeff>`
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**Default:** none
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.. _lws: http://lammps.sandia.gov
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.. _ld: Manual.html
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.. _lc: Commands_all.html
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