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lammps/doc/html/_sources/angle_hybrid.txt
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angle_hybrid.txt
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.. index:: angle_style hybrid
angle_style hybrid command
==========================
Syntax
""""""
.. parsed-literal::
angle_style hybrid style1 style2 ...
* style1,style2 = list of one or more angle styles
Examples
""""""""
.. parsed-literal::
angle_style hybrid harmonic cosine
angle_coeff 1 harmonic 80.0 30.0
angle_coeff 2* cosine 50.0
Description
"""""""""""
The *hybrid* style enables the use of multiple angle styles in one
simulation. An angle style is assigned to each angle type. For
example, angles in a polymer flow (of angle type 1) could be computed
with a *harmonic* potential and angles in the wall boundary (of angle
type 2) could be computed with a *cosine* potential. The assignment
of angle type to style is made via the :doc:`angle_coeff <angle_coeff>`
command or in the data file.
In the angle_coeff commands, the name of an angle style must be added
after the angle type, with the remaining coefficients being those
appropriate to that style. In the example above, the 2 angle_coeff
commands set angles of angle type 1 to be computed with a *harmonic*
potential with coefficients 80.0, 30.0 for K, theta0. All other angle
types (2-N) are computed with a *cosine* potential with coefficient
50.0 for K.
If angle 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 "cosine", must be added after the angle type, for each
line in the "Angle Coeffs" section, e.g.
.. parsed-literal::
Angle Coeffs
.. parsed-literal::
1 harmonic 80.0 30.0
2 cosine 50.0
...
If *class2* is one of the angle hybrid styles, the same rule holds for
specifying additional BondBond (and BondAngle) coefficients either via
the input script or in the data file. I.e. *class2* must be added to
each line after the angle type. For lines in the BondBond (or
BondAngle) section of the data file for angle types that are not
*class2*\ , you must use an angle style of *skip* as a placeholder, e.g.
.. parsed-literal::
BondBond Coeffs
.. parsed-literal::
1 skip
2 class2 3.6512 1.0119 1.0119
...
Note that it is not necessary to use the angle style *skip* in the
input script, since BondBond (or BondAngle) coefficients need not be
specified at all for angle types that are not *class2*\ .
An angle style of *none* with no additional coefficients can be used
in place of an angle style, either in a input script angle_coeff
command or in the data file, if you desire to turn off interactions
for specific angle types.
----------
Restrictions
""""""""""""
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.
Unlike other angle styles, the hybrid angle style does not store angle
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 angle_coeff commands.
Related commands
""""""""""""""""
:doc:`angle_coeff <angle_coeff>`
**Default:** none
.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm
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