forked from lijiext/lammps
116 lines
3.4 KiB
ReStructuredText
116 lines
3.4 KiB
ReStructuredText
.. index:: fix shardlow
|
|
|
|
fix shardlow command
|
|
====================
|
|
|
|
Syntax
|
|
""""""
|
|
|
|
.. parsed-literal::
|
|
|
|
fix ID group-ID shardlow
|
|
|
|
* ID, group-ID are documented in :doc:`fix <fix>` command
|
|
* shardlow = style name of this fix command
|
|
|
|
Examples
|
|
""""""""
|
|
|
|
.. parsed-literal::
|
|
|
|
fix 1 all shardlow
|
|
|
|
Description
|
|
"""""""""""
|
|
|
|
Specifies that the Shardlow splitting algorithm (SSA) is to be used to
|
|
integrate the DPD equations of motion. The SSA splits the integration
|
|
into a stochastic and deterministic integration step. The fix
|
|
*shardlow* performs the stochastic integration step and must be used
|
|
in conjunction with a deterministic integrator (e.g. :doc:`fix nve <fix_nve>` or :doc:`fix nph <fix_nph>`). The stochastic
|
|
integration of the dissipative and random forces is performed prior to
|
|
the deterministic integration of the conservative force. Further
|
|
details regarding the method are provided in :ref:`(Lisal) <Lisal>` and
|
|
:ref:`(Larentzos) <Larentzos>`.
|
|
|
|
The fix *shardlow* must be used with the :doc:`pair_style dpd/fdt <pair_style>` or :doc:`pair_style dpd/fdt/energy <pair_style>` command to properly initialize the
|
|
fluctuation-dissipation theorem parameter(s) sigma (and kappa, if
|
|
necessary).
|
|
|
|
Note that numerous variants of DPD can be specified by choosing an
|
|
appropriate combination of the integrator and :doc:`pair_style dpd/fdt <pair_style>` command. DPD under isothermal conditions can
|
|
be specified by using fix *shardlow*, fix *nve* and pair_style
|
|
*dpd/fdt*. DPD under isoenergetic conditions can be specified by
|
|
using fix *shardlow*, fix *nve* and pair_style *dpd/fdt/energy*. DPD
|
|
under isobaric conditions can be specified by using fix shardlow, fix
|
|
*nph* and pair_style *dpd/fdt*. DPD under isoenthalpic conditions can
|
|
be specified by using fix shardlow, fix *nph* and pair_style
|
|
*dpd/fdt/energy*. Examples of each DPD variant are provided in the
|
|
examples/USER/dpd directory.
|
|
|
|
|
|
----------
|
|
|
|
|
|
Restrictions
|
|
""""""""""""
|
|
|
|
|
|
This fix is only available if LAMMPS is built with the USER-DPD
|
|
package. See the :ref:`Making LAMMPS <start_3>` section
|
|
for more info.
|
|
|
|
This fix is currently limited to orthogonal simulation cell
|
|
geometries.
|
|
|
|
This fix must be used with an additional fix that specifies time
|
|
integration, e.g. :doc:`fix nve <fix_nve>` or :doc:`fix nph <fix_nh>`.
|
|
|
|
The Shardlow splitting algorithm requires the sizes of the sub-domain
|
|
lengths to be larger than twice the cutoff+skin. Generally, the
|
|
domain decomposition is dependant on the number of processors
|
|
requested.
|
|
|
|
Related commands
|
|
""""""""""""""""
|
|
|
|
:doc:`pair_style dpd/fdt <pair_dpd_fdt>`, :doc:`fix eos/cv <fix_eos_cv>`
|
|
|
|
**Default:** none
|
|
|
|
|
|
----------
|
|
|
|
|
|
.. _Lisal:
|
|
|
|
|
|
|
|
**(Lisal)** M. Lisal, J.K. Brennan, J. Bonet Avalos, "Dissipative
|
|
particle dynamics as isothermal, isobaric, isoenergetic, and
|
|
isoenthalpic conditions using Shardlow-like splitting algorithms.",
|
|
J. Chem. Phys., 135, 204105 (2011).
|
|
|
|
.. _Larentzos:
|
|
|
|
|
|
|
|
**(Larentzos)** J.P. Larentzos, J.K. Brennan, J.D. Moore, M. Lisal and
|
|
W.D. Mattson, "Parallel Implementation of Isothermal and Isoenergetic
|
|
Dissipative Particle Dynamics Using Shardlow-Like Splitting
|
|
Algorithms", Comput. Phys. Commun., 185, 1987-1998 (2014).
|
|
|
|
.. _Larentzos:
|
|
|
|
|
|
|
|
**(Larentzos)** J.P. Larentzos, J.K. Brennan, J.D. Moore, and
|
|
W.D. Mattson, "LAMMPS Implementation of Constant Energy Dissipative
|
|
Particle Dynamics (DPD-E)", ARL-TR-6863, U.S. Army Research
|
|
Laboratory, Aberdeen Proving Ground, MD (2014).
|
|
|
|
|
|
.. _lws: http://lammps.sandia.gov
|
|
.. _ld: Manual.html
|
|
.. _lc: Section_commands.html#comm
|