162 lines
5.4 KiB
ReStructuredText
162 lines
5.4 KiB
ReStructuredText
.. index:: pair\_style brownian
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pair\_style brownian command
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============================
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pair\_style brownian/omp command
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================================
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pair\_style brownian/poly command
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=================================
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pair\_style brownian/poly/omp 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 style mu flaglog flagfld cutinner cutoff t_target seed flagHI flagVF
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* style = *brownian* or *brownian/poly*
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* mu = dynamic viscosity (dynamic viscosity units)
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* flaglog = 0/1 log terms in the lubrication approximation on/off
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* flagfld = 0/1 to include/exclude Fast Lubrication Dynamics effects
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* cutinner = inner cutoff distance (distance units)
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* cutoff = outer cutoff for interactions (distance units)
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* t\_target = target temp of the system (temperature units)
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* seed = seed for the random number generator (positive integer)
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* flagHI (optional) = 0/1 to include/exclude 1/r hydrodynamic interactions
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* flagVF (optional) = 0/1 to include/exclude volume fraction corrections in the long-range isotropic terms
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Examples
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""""""""
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.. parsed-literal::
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pair_style brownian 1.5 1 1 2.01 2.5 2.0 5878567 (assuming radius = 1)
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pair_coeff 1 1 2.05 2.8
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pair_coeff \* \*
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Description
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"""""""""""
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Styles *brownian* and *brownian/poly* compute Brownian forces and
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torques on finite-size spherical particles. The former requires
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monodisperse spherical particles; the latter allows for polydisperse
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spherical particles.
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These pair styles are designed to be used with either the :doc:`pair\_style lubricate <pair_lubricate>` or :doc:`pair\_style lubricateU <pair_lubricateU>` commands to provide thermostatting
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when dissipative lubrication forces are acting. Thus the parameters
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*mu*\ , *flaglog*\ , *flagfld*\ , *cutinner*\ , and *cutoff* should be
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specified consistent with the settings in the lubrication pair styles.
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For details, refer to either of the lubrication pair styles.
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The *t\_target* setting is used to specify the target temperature of
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the system. The random number *seed* is used to generate random
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numbers for the thermostatting procedure.
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The *flagHI* and *flagVF* settings are optional. Neither should be
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used, or both must be defined.
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----------
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The following coefficients must be defined for each pair of atoms
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types via the :doc:`pair\_coeff <pair_coeff>` command as in the examples
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above, or in the data file or restart files read by the
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:doc:`read\_data <read_data>` or :doc:`read\_restart <read_restart>`
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commands, or by mixing as described below:
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* cutinner (distance units)
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* cutoff (distance units)
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The two coefficients are optional. If neither is specified, the two
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cutoffs specified in the pair\_style command are used. Otherwise both
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must be specified.
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----------
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Styles with a *gpu*\ , *intel*\ , *kk*\ , *omp*\ , or *opt* suffix are
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functionally the same as the corresponding style without the suffix.
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They have been optimized to run faster, depending on your available
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hardware, as discussed in :doc:`this section <Speed>` of
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the manual. The accelerated styles take the same arguments and should
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produce the same results, except for round-off and precision issues.
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These accelerated styles are part of the GPU, USER-INTEL, KOKKOS,
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USER-OMP and OPT packages, respectively. They are only enabled if
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LAMMPS was built with those packages. See the :doc:`Build package <Build_package>` doc page for more info.
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You can specify the accelerated styles explicitly in your input script
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by including their suffix, or you can use the :doc:`-suffix command-line switch <Run_options>` when you invoke LAMMPS, or you can use the
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:doc:`suffix <suffix>` command in your input script.
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See :doc:`this section <Speed>` of the manual for more
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instructions on how to use the accelerated styles effectively.
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----------
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**Mixing, shift, table, tail correction, restart, rRESPA info**\ :
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For atom type pairs I,J and I != J, the two cutoff distances for this
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pair style can be mixed. The default mix value is *geometric*\ . See
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the "pair\_modify" command for details.
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This pair style does not support the :doc:`pair\_modify <pair_modify>`
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shift option for the energy of the pair interaction.
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The :doc:`pair\_modify <pair_modify>` table option is not relevant
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for this pair style.
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This pair style does not support the :doc:`pair\_modify <pair_modify>`
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tail option for adding long-range tail corrections to energy and
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pressure.
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This pair style writes its information to :doc:`binary restart files <restart>`, so pair\_style and pair\_coeff commands do not need
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to be specified in an input script that reads a restart file.
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This pair style can only be used via the *pair* keyword of the
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:doc:`run\_style respa <run_style>` command. It does not support the
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*inner*\ , *middle*\ , *outer* keywords.
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----------
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Restrictions
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""""""""""""
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These styles are part of the COLLOID package. They are only enabled
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if LAMMPS was built with that package. See the :doc:`Build package <Build_package>` doc page for more info.
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Only spherical monodisperse particles are allowed for pair\_style
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brownian.
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Only spherical particles are allowed for pair\_style brownian/poly.
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Related commands
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""""""""""""""""
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:doc:`pair\_coeff <pair_coeff>`, :doc:`pair\_style lubricate <pair_lubricate>`, :doc:`pair\_style lubricateU <pair_lubricateU>`
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Default
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"""""""
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The default settings for the optional args are flagHI = 1 and flagVF =
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1.
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.. _lws: http://lammps.sandia.gov
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.. _ld: Manual.html
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.. _lc: Commands_all.html
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