forked from lijiext/lammps
89 lines
2.5 KiB
Plaintext
89 lines
2.5 KiB
Plaintext
.. index:: bond_style hybrid
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bond_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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bond_style hybrid style1 style2 ...
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* style1,style2 = list of one or more bond styles
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Examples
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""""""""
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.. parsed-literal::
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bond_style hybrid harmonic fene
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bond_coeff 1 harmonic 80.0 1.2
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bond_coeff 2* fene 30.0 1.5 1.0 1.0
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Description
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"""""""""""
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The *hybrid* style enables the use of multiple bond styles in one
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simulation. A bond style is assigned to each bond type. For example,
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bonds in a polymer flow (of bond type 1) could be computed with a
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*fene* potential and bonds in the wall boundary (of bond type 2) could
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be computed with a *harmonic* potential. The assignment of bond type
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to style is made via the :doc:`bond_coeff <bond_coeff>` command or in
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the data file.
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In the bond_coeff commands, the name of a bond style must be added
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after the bond type, with the remaining coefficients being those
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appropriate to that style. In the example above, the 2 bond_coeff
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commands set bonds of bond type 1 to be computed with a *harmonic*
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potential with coefficients 80.0, 1.2 for K, r0. All other bond types
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(2-N) are computed with a *fene* potential with coefficients 30.0,
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1.5, 1.0, 1.0 for K, R0, epsilon, sigma.
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If bond coefficients are specified in the data file read via the
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:doc:`read_data <read_data>` command, then the same rule applies.
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E.g. "harmonic" or "fene" must be added after the bond type, for each
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line in the "Bond Coeffs" section, e.g.
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.. parsed-literal::
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Bond Coeffs
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.. parsed-literal::
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1 harmonic 80.0 1.2
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2 fene 30.0 1.5 1.0 1.0
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...
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A bond style of *none* with no additional coefficients can be used in
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place of a bond style, either in a input script bond_coeff command or
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in the data file, if you desire to turn off interactions for specific
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bond types.
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----------
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Restrictions
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""""""""""""
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This bond 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 bond styles, the hybrid bond style does not store bond
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coefficient info for individual sub-styles in a :doc:`binary restart files <restart>`. Thus when retarting a simulation from a restart
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file, you need to re-specify bond_coeff commands.
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Related commands
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""""""""""""""""
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:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`
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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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