.. index:: pair_style dpd/conservative

pair_style dpd/conservative command
===================================

Syntax
""""""

.. parsed-literal::

   pair_style dpd/conservative cutoff

* cutoff = global cutoff for DPD interactions (distance units)

Examples
""""""""

.. parsed-literal::

   pair_style dpd/conservative 2.5
   pair_coeff * * 3.0 2.5
   pair_coeff 1 1 3.0

Description
"""""""""""

Style *dpd/conservative* computes the conservative force for
dissipative particle dynamics (DPD).  The conservative force on atom I
due to atom J is given by

.. image:: Eqs/pair_dpd_conservative.jpg
   :align: center

where the weighting factor, omega_ij, varies between 0 and 1, and is
chosen to have the following functional form:

.. image:: Eqs/pair_dpd_omega.jpg
   :align: center

where Rij is a unit vector in the direction Ri - Rj, and Rc is the
cutoff.  Note that alternative definitions of the weighting function
exist, but would have to be implemented as a separate pair style
command.

Style *dpd/conservative* differs from the other dpd styles in that the
dissipative and random forces are not computed within the pair style.

For style *dpd/conservative*\ , the pairwise energy is due only to the
conservative force term Fc, and is shifted to be zero at the cutoff
distance Rc.  The pairwise virial is calculated using only the
conservative term.

Style *dpd/conservative* requires the following coefficients to be
defined for each pair of atoms types via the
:doc:`pair_coeff <pair_coeff>` command as in the examples above, or in
the data file or restart files read by the :doc:`read_data <read_data>`
or :doc:`read_restart <read_restart>` commands:

* A (force units)
* cutoff (distance units)

The last coefficient is optional.  If not specified, the global DPD
cutoff is used.


----------


Restrictions
""""""""""""


The pair style *dpd/conservative* is only available if LAMMPS is built
with the USER-DPD package.

Related commands
""""""""""""""""

:doc:`pair_coeff <pair_coeff>`, :doc:`pair_dpd <pair_dpd>`

**Default:** none


.. _lws: http://lammps.sandia.gov
.. _ld: Manual.html
.. _lc: Section_commands.html#comm