forked from lijiext/lammps
81 lines
2.5 KiB
Plaintext
81 lines
2.5 KiB
Plaintext
.. index:: improper_style hybrid
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improper_style hybrid command
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=============================
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Syntax
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""""""
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.. parsed-literal::
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improper_style hybrid style1 style2 ...
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* style1,style2 = list of one or more improper styles
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Examples
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""""""""
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.. parsed-literal::
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improper_style hybrid harmonic helix
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improper_coeff 1 harmonic 120.0 30
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improper_coeff 2 cvff 20.0 -1 2
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Description
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"""""""""""
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The *hybrid* style enables the use of multiple improper styles in one
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simulation. An improper style is assigned to each improper type. For
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example, impropers in a polymer flow (of improper type 1) could be
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computed with a *harmonic* potential and impropers in the wall
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boundary (of improper type 2) could be computed with a *cvff*
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potential. The assignment of improper type to style is made via the
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:doc:`improper_coeff <improper_coeff>` command or in the data file.
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In the improper_coeff command, the first coefficient sets the improper
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style and the remaining coefficients are those appropriate to that
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style. In the example above, the 2 improper_coeff commands would set
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impropers of improper type 1 to be computed with a *harmonic*
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potential with coefficients 120.0, 30 for K, X0. Improper type 2
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would be computed with a *cvff* potential with coefficients 20.0, -1,
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2 for K, d, n.
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If the improper *class2* potential is one of the hybrid styles, it
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requires additional AngleAngle coefficients be specified in the data
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file. These lines must also have an additional "class2" argument
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added after the improper type. For improper types which are assigned
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to other hybrid styles, use the style name (e.g. "harmonic")
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appropriate to that style. The AngleAngle coeffs for that improper
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type will then be ignored.
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An improper style of *none* can be specified as the 2nd argument to
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the improper_coeff command, if you desire to turn off certain improper
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types.
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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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MOLECULE package (which it is by default). See the :ref:`Making LAMMPS <start_3>` section for more info on packages.
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Unlike other improper styles, the hybrid improper style does not store
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improper coefficient info for individual sub-styles in a :doc:`binary restart files <restart>`. Thus when retarting a simulation from a
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restart file, you need to re-specify improper_coeff commands.
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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: Section_commands.html#comm
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