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