fix broken doc page links to new fix sph commands

.. note::

   The particles affected by this fix should not be time integrated

   by other fixes (e.g. :doc:`fix meso <fix_meso>`, :doc:`fix meso/stationary <fix_meso_stationary>`), since that will change their

   The particles affected by this fix should not be time integrated by

   other fixes (e.g. :doc:`fix sph <fix_sph>`, :doc:`fix

   sph/stationary <fix_sph_stationary>`), since that will change their

   positions and velocities twice.

.. note::

   As particles move due to this fix, they will pass through periodic

   boundaries and be remapped to the other side of the simulation box,

   just as they would during normal time integration (e.g. via the :doc:`fix meso <fix_meso>` command).  It is up to you to decide whether periodic

   boundaries are appropriate with the kind of particle motion you are

   prescribing with this fix.

   just as they would during normal time integration (e.g. via the

   :doc:`fix sph <fix_sph>` command).  It is up to you to decide

   whether periodic boundaries are appropriate with the kind of

   particle motion you are prescribing with this fix.

.. note::

specified.  This style also sets the velocity of each particle to V =

(Vx,Vy,Vz).  If any of the velocity components is specified as NULL,

then the position and velocity of that component is time integrated

the same as the :doc:`fix meso <fix_meso>` command would perform, using

the same as the :doc:`fix sph <fix_sph>` command would perform, using

the corresponding force component on the particle.

Note that the *linear* style is identical to using the *variable*

velocity of each particle to the time derivative of this expression.

If any of the amplitude components is specified as NULL, then the

position and velocity of that component is time integrated the same as

the :doc:`fix meso <fix_meso>` command would perform, using the

the :doc:`fix sph <fix_sph>` command would perform, using the

corresponding force component on the particle.

Note that the *wiggle* style is identical to using the *variable*

Any of the 6 variables can be specified as NULL.  If both the

displacement and velocity variables for a particular x,y,z component

are specified as NULL, then the position and velocity of that

component is time integrated the same as the :doc:`fix meso <fix_meso>`

component is time integrated the same as the :doc:`fix sph <fix_sph>`

command would perform, using the corresponding force component on the

particle.  If only the velocity variable for a component is specified as

NULL, then the displacement variable will be used to set the position

of the particle, and its velocity component will not be changed. If only

the displacement variable for a component is specified as NULL, then

the velocity variable will be used to set the velocity of the particle,

and the position of the particle will be time integrated using that

velocity.

particle.  If only the velocity variable for a component is specified

as NULL, then the displacement variable will be used to set the

position of the particle, and its velocity component will not be

changed. If only the displacement variable for a component is

specified as NULL, then the velocity variable will be used to set the

velocity of the particle, and the position of the particle will be

time integrated using that velocity.

The *units* keyword determines the meaning of the distance units used

to define the *linear* velocity and *wiggle* amplitude and *rotate*

""""""""""""

This fix is part of the USER-SDPD package.  It is only enabled if

LAMMPS was built with that package. See the :doc:`Build package <Build_package>` doc page for more info.

LAMMPS was built with that package. See the :doc:`Build package

<Build_package>` doc page for more info.

This fix requires that atoms store density and internal energy as

defined by the :doc:`atom_style meso <atom_style>` command.

defined by the :doc:`atom_style sph <atom_style>` command.

All particles in the group must be mesoscopic SPH/SDPD particles.

Related commands

""""""""""""""""

:doc:`fix move <fix_move>`, :doc:`fix meso <fix_meso>`,

:doc:`fix move <fix_move>`, :doc:`fix sph <fix_sph>`,

:doc:`displace_atoms <displace_atoms>`

Default

.. note::

   You should not update the particles in rigid bodies via other

   time-integration fixes (e.g. :doc:`fix meso <fix_meso>`,

   :doc:`fix meso/stationary <fix_meso_stationary>`), or you will have conflicting

   updates to positions and velocities resulting in unphysical behavior in most

   cases. When performing a hybrid simulation with some atoms in rigid bodies,

   and some not, a separate time integration fix like :doc:`fix meso <fix_meso>`

   should be used for the non-rigid particles.

   time-integration fixes (e.g. :doc:`fix sph <fix_sph>`, :doc:`fix

   sph/stationary <fix_sph_stationary>`), or you will have conflicting

   updates to positions and velocities resulting in unphysical

   behavior in most cases. When performing a hybrid simulation with

   some atoms in rigid bodies, and some not, a separate time

   integration fix like :doc:`fix sph <fix_sph>` should be used for

   the non-rigid particles.

.. note::

   These fixes are overkill if you simply want to hold a collection

   of particles stationary or have them move with a constant velocity. To

   hold particles stationary use :doc:`fix meso/stationary <fix_meso_stationary>` instead. If you would like to

   move particles with a constant velocity use :doc:`fix meso/move <fix_meso_move>`.

   These fixes are overkill if you simply want to hold a collection of

   particles stationary or have them move with a constant velocity. To

   hold particles stationary use :doc:`fix sph/stationary

   <fix_sph_stationary>` instead. If you would like to move particles

   with a constant velocity use :doc:`fix meso/move <fix_meso_move>`.

.. warning::

the :doc:`Build package <Build_package>` doc page for more info.

This fix requires that atoms store density and internal energy as

defined by the :doc:`atom_style meso <atom_style>` command.

defined by the :doc:`atom_style sph <atom_style>` command.

All particles in the group must be mesoscopic SPH/SDPD particles.