mirror of https://github.com/lammps/lammps.git
87 lines
2.1 KiB
Plaintext
87 lines
2.1 KiB
Plaintext
.. index:: pair_style dpd/conservative
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pair_style dpd/conservative command
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===================================
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Syntax
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""""""
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.. parsed-literal::
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pair_style dpd/conservative cutoff
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* cutoff = global cutoff for DPD interactions (distance units)
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Examples
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""""""""
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.. parsed-literal::
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pair_style dpd/conservative 2.5
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pair_coeff * * 3.0 2.5
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pair_coeff 1 1 3.0
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Description
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"""""""""""
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Style *dpd/conservative* computes the conservative force for
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dissipative particle dynamics (DPD). The conservative force on atom I
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due to atom J is given by
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.. image:: Eqs/pair_dpd_conservative.jpg
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:align: center
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where the weighting factor, omega_ij, varies between 0 and 1, and is
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chosen to have the following functional form:
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.. image:: Eqs/pair_dpd_omega.jpg
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:align: center
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where Rij is a unit vector in the direction Ri - Rj, and Rc is the
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cutoff. Note that alternative definitions of the weighting function
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exist, but would have to be implemented as a separate pair style
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command.
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Style *dpd/conservative* differs from the other dpd styles in that the
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dissipative and random forces are not computed within the pair style.
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For style *dpd/conservative*\ , the pairwise energy is due only to the
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conservative force term Fc, and is shifted to be zero at the cutoff
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distance Rc. The pairwise virial is calculated using only the
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conservative term.
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Style *dpd/conservative* requires the following coefficients to be
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defined for each pair of atoms types via the
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:doc:`pair_coeff <pair_coeff>` command as in the examples above, or in
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the data file or restart files read by the :doc:`read_data <read_data>`
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or :doc:`read_restart <read_restart>` commands:
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* A (force units)
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* cutoff (distance units)
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The last coefficient is optional. If not specified, the global DPD
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cutoff is used.
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----------
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Restrictions
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""""""""""""
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The pair style *dpd/conservative* is only available if LAMMPS is built
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with the USER-DPD package.
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Related commands
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""""""""""""""""
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:doc:`pair_coeff <pair_coeff>`, :doc:`pair_dpd <pair_dpd>`
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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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