.. index:: pair_style brownian pair_style brownian command =========================== pair_style brownian/omp command =============================== pair_style brownian/poly command ================================ pair_style brownian/poly/omp command ==================================== Syntax """""" .. parsed-literal:: pair_style style mu flaglog flagfld cutinner cutoff t_target seed flagHI flagVF * style = *brownian* or *brownian/poly* * mu = dynamic viscosity (dynamic viscosity units) * flaglog = 0/1 log terms in the lubrication approximation on/off * flagfld = 0/1 to include/exclude Fast Lubrication Dynamics effects * cutinner = inner cutoff distance (distance units) * cutoff = outer cutoff for interactions (distance units) * t_target = target temp of the system (temperature units) * seed = seed for the random number generator (positive integer) * flagHI (optional) = 0/1 to include/exclude 1/r hydrodynamic interactions * flagVF (optional) = 0/1 to include/exclude volume fraction corrections in the long-range isotropic terms Examples """""""" .. parsed-literal:: pair_style brownian 1.5 1 1 2.01 2.5 2.0 5878567 (assuming radius = 1) pair_coeff 1 1 2.05 2.8 pair_coeff * * Description """"""""""" Styles *brownian* and *brownain/poly* compute Brownian forces and torques on finite-size spherical particles. The former requires monodisperse spherical particles; the latter allows for polydisperse spherical particles. These pair styles are designed to be used with either the :doc:`pair_style lubricate ` or :doc:`pair_style lubricateU ` commands to provide thermostatting when dissipative lubrication forces are acting. Thus the parameters *mu*\ , *flaglog*\ , *flagfld*\ , *cutinner*\ , and *cutoff* should be specified consistent with the settings in the lubrication pair styles. For details, refer to either of the lubrication pair styles. The *t_target* setting is used to specify the target temperature of the system. The random number *seed* is used to generate random numbers for the thermostatting procedure. The *flagHI* and *flagVF* settings are optional. Neither should be used, or both must be defined. ---------- The following coefficients must be defined for each pair of atoms types via the :doc:`pair_coeff ` command as in the examples above, or in the data file or restart files read by the :doc:`read_data ` or :doc:`read_restart ` commands, or by mixing as described below: * cutinner (distance units) * cutoff (distance units) The two coefficients are optional. If neither is specified, the two cutoffs specified in the pair_style command are used. Otherwise both must be specified. ---------- Styles with a *cuda*\ , *gpu*\ , *intel*\ , *kk*\ , *omp*\ , or *opt* suffix are functionally the same as the corresponding style without the suffix. They have been optimized to run faster, depending on your available hardware, as discussed in :doc:`this section ` of the manual. The accelerated styles take the same arguments and should produce the same results, except for round-off and precision issues. These accelerated styles are part of the USER-CUDA, GPU, USER-INTEL, KOKKOS, USER-OMP and OPT packages, respectively. They are only enabled if LAMMPS was built with those packages. See the :ref:`Making LAMMPS ` section for more info. You can specify the accelerated styles explicitly in your input script by including their suffix, or you can use the :ref:`-suffix command-line switch ` when you invoke LAMMPS, or you can use the :doc:`suffix ` command in your input script. See :doc:`this section ` of the manual for more instructions on how to use the accelerated styles effectively. ---------- **Mixing, shift, table, tail correction, restart, rRESPA info**\ : For atom type pairs I,J and I != J, the two cutoff distances for this pair style can be mixed. The default mix value is *geometric*\ . See the "pair_modify" command for details. This pair style does not support the :doc:`pair_modify ` shift option for the energy of the pair interaction. The :doc:`pair_modify ` table option is not relevant for this pair style. This pair style does not support the :doc:`pair_modify ` tail option for adding long-range tail corrections to energy and pressure. This pair style writes its information to :doc:`binary restart files `, so pair_style and pair_coeff commands do not need to be specified in an input script that reads a restart file. This pair style can only be used via the *pair* keyword of the :doc:`run_style respa ` command. It does not support the *inner*\ , *middle*\ , *outer* keywords. ---------- Restrictions """""""""""" These styles are part of the COLLOID package. They are only enabled if LAMMPS was built with that package. See the :ref:`Making LAMMPS <2_3>` section for more info. Only spherical monodisperse particles are allowed for pair_style brownian. Only spherical particles are allowed for pair_style brownian/poly. Related commands """""""""""""""" :doc:`pair_coeff `, :doc:`pair_style lubricate `, :doc:`pair_style lubricateU ` Default """"""" The default settings for the optional args are flagHI = 1 and flagVF = 1. .. _lws: http://lammps.sandia.gov .. _ld: Manual.html .. _lc: Section_commands.html#comm