Homec4science
Diffusion lammps (lammps-icms) Browse

lammps/doc/_sources/bond_hybrid.txt
874bd68cd12flammps-icms

Last Change
Raw File

bond_hybrid.txt
View Options

.. index:: bond_style hybrid
bond_style hybrid command
=========================
Syntax
""""""
.. parsed-literal::
bond_style hybrid style1 style2 ...
* style1,style2 = list of one or more bond styles
Examples
""""""""
.. parsed-literal::
bond_style hybrid harmonic fene
bond_coeff 1 harmonic 80.0 1.2
bond_coeff 2* fene 30.0 1.5 1.0 1.0
Description
"""""""""""
The *hybrid* style enables the use of multiple bond styles in one
simulation. A bond style is assigned to each bond type. For example,
bonds in a polymer flow (of bond type 1) could be computed with a
*fene* potential and bonds in the wall boundary (of bond type 2) could
be computed with a *harmonic* potential. The assignment of bond type
to style is made via the :doc:`bond_coeff <bond_coeff>` command or in
the data file.
In the bond_coeff commands, the name of a bond style must be added
after the bond type, with the remaining coefficients being those
appropriate to that style. In the example above, the 2 bond_coeff
commands set bonds of bond type 1 to be computed with a *harmonic*
potential with coefficients 80.0, 1.2 for K, r0. All other bond types
(2-N) are computed with a *fene* potential with coefficients 30.0,
1.5, 1.0, 1.0 for K, R0, epsilon, sigma.
If bond coefficients are specified in the data file read via the
:doc:`read_data <read_data>` command, then the same rule applies.
E.g. "harmonic" or "fene" must be added after the bond type, for each
line in the "Bond Coeffs" section, e.g.
.. parsed-literal::
Bond Coeffs
.. parsed-literal::
1 harmonic 80.0 1.2
2 fene 30.0 1.5 1.0 1.0
...
A bond style of *none* with no additional coefficients can be used in
place of a bond style, either in a input script bond_coeff command or
in the data file, if you desire to turn off interactions for specific
bond types.
----------
Restrictions
""""""""""""
This bond 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.
Unlike other bond styles, the hybrid bond style does not store bond
coefficient info for individual sub-styles in a :doc:`binary restart files <restart>`. Thus when retarting a simulation from a restart
file, you need to re-specify bond_coeff commands.
Related commands
""""""""""""""""
:doc:`bond_coeff <bond_coeff>`, :doc:`delete_bonds <delete_bonds>`
**Default:** none
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
c4science · Help