update docs to make wall fix restrictions more explicit
This commit is contained in:
Axel Kohlmeyer
@ -97,27 +97,28 @@ corrections to R_FU are included if *flagVF* is set to 1 (default).
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F\ *rest* represents the forces and torques due to all other types of
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interactions, e.g. Brownian, electrostatic etc. Note that this
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algorithm neglects the inertial terms, thereby removing the
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restriction of resolving the small interial time scale, which may not
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be of interest for colloidal particles. This pair style solves for
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the velocity such that the hydrodynamic force balances all other types
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of forces, thereby resulting in a net zero force (zero inertia limit).
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When defining this pair style, it must be defined last so that when
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this style is invoked all other types of forces have already been
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computed. For the same reason, it won't work if additional non-pair
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styles are defined (such as bond or Kspace forces) as they are
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calculated in LAMMPS after the pairwise interactions have been
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computed.
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algorithm neglects the inertial terms, thereby removing the restriction
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of resolving the small interial time scale, which may not be of interest
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for colloidal particles. These pair styles solve for the velocity such
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that the hydrodynamic force balances all other types of forces, thereby
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resulting in a net zero force (zero inertia limit). When defining these
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pair styles, they must be defined last so that when these styles are
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invoked all other types of forces have already been computed. For the
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same reason, they won't work if additional non-pair styles are defined
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(such as bond or Kspace forces) as they are calculated in LAMMPS after
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the pairwise interactions have been computed.
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.. note::
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When using these styles, the these pair styles are designed to
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be used with implicit time integration and a correspondingly larger
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timestep. Thus either :doc:`fix nve/noforce <fix_nve_noforce>` should
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be used for spherical particles defined via :doc:`atom_style sphere <atom_style>` or :doc:`fix nve/asphere/noforce <fix_nve_asphere_noforce>` should be used for
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spherical particles defined via :doc:`atom_style ellipsoid <atom_style>`. This is because the velocity and angular
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momentum of each particle is set by the pair style, and should not be
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reset by the time integration fix.
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When using these styles, the pair styles are designed to be used with
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implicit time integration and a correspondingly larger timestep.
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Thus either :doc:`fix nve/noforce <fix_nve_noforce>` should be used
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for spherical particles defined via :doc:`atom_style sphere
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<atom_style>` or :doc:`fix nve/asphere/noforce
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<fix_nve_asphere_noforce>` should be used for spherical particles
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defined via :doc:`atom_style ellipsoid <atom_style>`. This is
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because the velocity and angular momentum of each particle is set by
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the pair style, and should not be reset by the time integration fix.
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Style *lubricateU* requires monodisperse spherical particles; style
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*lubricateU/poly* allows for polydisperse spherical particles.
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@ -128,17 +129,20 @@ hydrodynamic interactions accordingly. Volume changes due to fix
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deform are accounted for when computing the volume fraction
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corrections to R_FU.
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When computing the volume fraction corrections to R_FU, the presence
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of walls (whether moving or stationary) will affect the volume
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fraction available to colloidal particles. This is currently accounted
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for with the following types of walls: :doc:`wall/lj93 <fix_wall>`,
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When computing the volume fraction corrections to R_FU, the presence of
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walls (whether moving or stationary) will affect the volume fraction
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available to colloidal particles. This is currently accounted for with
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the following types of walls: :doc:`wall/lj93 <fix_wall>`,
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:doc:`wall/lj126 <fix_wall>`, :doc:`wall/colloid <fix_wall>`, and
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:doc:`wall/harmonic <fix_wall>`. For these wall styles, the correct
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volume fraction will be used when walls do not coincide with the box
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boundary, as well as when walls move and thereby cause a change in the
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volume fraction. To use these wall styles with pair_style *lubricateU*
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or *lubricateU/poly*, the *fld yes* option must be specified in the
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fix wall command.
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or *lubricateU/poly*, the *fld yes* option must be specified in the fix
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wall command. Other wall styles may still work, but they will result
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in the volume fraction being computed based on the box boundaries.
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Several wall styles are not compatible with these pair styles and using
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them will result in an error.
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Since lubrication forces are dissipative, it is usually desirable to
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thermostat the system at a constant temperature. If Brownian motion
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@ -171,21 +175,22 @@ 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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These pair styles do 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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for these pair styles.
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This pair style does not support the :doc:`pair_modify <pair_modify>`
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These pair styles do 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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These pair styles write their information to :doc:`binary restart files
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<restart>`, so pair_style and pair_coeff commands do not need to be
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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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These pair styles can only be used via the *pair* keyword of the
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:doc:`run_style respa <run_style>` command. They does not support the
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*inner*, *middle*, *outer* keywords.
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----------
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@ -193,24 +198,31 @@ This pair style can only be used via the *pair* keyword of the
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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>` page for more info.
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These styles are part of the COLLOID package. They are only enabled if
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LAMMPS was built with that package. See the :doc:`Build package
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<Build_package>` page for more info.
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Currently, these pair styles assume that all other types of
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forces/torques on the particles have been already been computed when
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it is invoked. This requires this style to be defined as the last of
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the pair styles, and that no fixes apply additional constraint forces.
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One exception is the :doc:`fix wall/colloid <fix_wall>` commands, which
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has an "fld" option to apply their wall forces correctly.
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forces/torques on the particles have been already been computed when it
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is invoked. This requires this style to be defined as the last of the
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pair styles, and that no fixes apply additional constraint forces. One
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exception is the :doc:`fix wall/colloid <fix_wall>` commands, which has
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an "fld" option to apply their wall forces correctly.
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Only spherical monodisperse particles are allowed for pair_style
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lubricateU.
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Only spherical particles are allowed for pair_style lubricateU/poly.
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For sheared suspensions, it is assumed that the shearing is done in
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the xy plane, with x being the velocity direction and y being the
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velocity-gradient direction. In this case, one must use :doc:`fix deform <fix_deform>` with the same rate of shear (erate).
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For sheared suspensions, it is assumed that the shearing is done in the
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xy plane, with x being the velocity direction and y being the
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velocity-gradient direction. In this case, one must use :doc:`fix deform
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<fix_deform>` with the same rate of shear (erate).
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These pair styles are only compatible with the following wall fixes:
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doc:`fix wall/lj93, fix wall/lj126, fix wall/lj1043, fix wall/colloid,
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fix wall/harmonic, fix wall/lepton, fix wall/morse, fix wall/table
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<fix_wall>`.
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Related commands
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""""""""""""""""
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