109 lines
3.5 KiB
ReStructuredText
109 lines
3.5 KiB
ReStructuredText
.. index:: fix shardlow
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.. index:: fix shardlow/kk
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fix shardlow command
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====================
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Accelerator Variants: *shardlow/kk*
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Syntax
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""""""
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.. code-block:: LAMMPS
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fix ID group-ID shardlow
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* ID, group-ID are documented in :doc:`fix <fix>` command
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* shardlow = style name of this fix command
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Examples
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""""""""
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.. code-block:: LAMMPS
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fix 1 all shardlow
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Description
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"""""""""""
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Specifies that the Shardlow splitting algorithm (SSA) is to be used to
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integrate the DPD equations of motion. The SSA splits the integration
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into a stochastic and deterministic integration step. The fix
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*shardlow* performs the stochastic integration step and must be used
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in conjunction with a deterministic integrator (e.g. :doc:`fix nve <fix_nve>` or :doc:`fix nph <fix_nh>`). The stochastic
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integration of the dissipative and random forces is performed prior to
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the deterministic integration of the conservative force. Further
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details regarding the method are provided in :ref:`(Lisal) <Lisal>` and
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:ref:`(Larentzos1) <Larentzos1sh>`.
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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
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fluctuation-dissipation theorem parameter(s) sigma (and kappa, if
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necessary).
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Note that numerous variants of DPD can be specified by choosing an
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appropriate combination of the integrator and :doc:`pair_style dpd/fdt <pair_style>` command. DPD under isothermal conditions can
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be specified by using fix *shardlow*, fix *nve* and pair_style
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*dpd/fdt*\ . DPD under isoenergetic conditions can be specified by
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using fix *shardlow*, fix *nve* and pair_style *dpd/fdt/energy*\ . DPD
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under isobaric conditions can be specified by using fix shardlow, fix
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*nph* and pair_style *dpd/fdt*\ . DPD under isoenthalpic conditions can
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be specified by using fix shardlow, fix *nph* and pair_style
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*dpd/fdt/energy*\ . Examples of each DPD variant are provided in the
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examples/PACKAGES/dpd-react directory.
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----------
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.. include:: accel_styles.rst
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----------
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Restrictions
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""""""""""""
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This command is part of the DPD-REACT package. It is only enabled if
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LAMMPS was built with that package. See the :doc:`Build package <Build_package>` page for more info.
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This fix is currently limited to orthogonal simulation cell
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geometries.
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This fix must be used with an additional fix that specifies time
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integration, e.g. :doc:`fix nve <fix_nve>` or :doc:`fix nph <fix_nh>`.
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The Shardlow splitting algorithm requires the sizes of the subdomain
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lengths to be larger than twice the cutoff+skin. Generally, the
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domain decomposition is dependent on the number of processors
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requested.
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Related commands
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""""""""""""""""
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:doc:`pair_style dpd/fdt <pair_dpd_fdt>`, :doc:`fix eos/cv <fix_eos_cv>`
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Default
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"""""""
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none
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----------
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.. _Lisal:
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**(Lisal)** M. Lisal, J.K. Brennan, J. Bonet Avalos, "Dissipative
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particle dynamics as isothermal, isobaric, isoenergetic, and
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isoenthalpic conditions using Shardlow-like splitting algorithms.",
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J. Chem. Phys., 135, 204105 (2011).
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.. _Larentzos1sh:
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**(Larentzos1)** J.P. Larentzos, J.K. Brennan, J.D. Moore, M. Lisal and
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W.D. Mattson, "Parallel Implementation of Isothermal and Isoenergetic
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Dissipative Particle Dynamics Using Shardlow-Like Splitting
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Algorithms", Comput. Phys. Commun., 185, 1987-1998 (2014).
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.. _Larentzos2sh:
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**(Larentzos2)** J.P. Larentzos, J.K. Brennan, J.D. Moore, and
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W.D. Mattson, "LAMMPS Implementation of Constant Energy Dissipative
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Particle Dynamics (DPD-E)", ARL-TR-6863, U.S. Army Research
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Laboratory, Aberdeen Proving Ground, MD (2014).
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