fix shardlow command¶
Syntax¶
fix ID group-ID shardlow
- ID, group-ID are documented in fix command
- shardlow = style name of this fix command
Examples¶
fix 1 all shardlow
Description¶
Specifies that the Shardlow splitting algorithm (SSA) is to be used to
integrate the DPD equations of motion. The SSA splits the integration
into a stochastic and deterministic integration step. The fix
shardlow performs the stochastic integration step and must be used
in conjunction with a deterministic integrator (e.g. fix nve or fix nph
). The stochastic
integration of the dissipative and random forces is performed prior to
the deterministic integration of the conservative force. Further
details regarding the method are provided in (Lisal) and
(Larentzos).
The fix shardlow must be used with the pair_style dpd/fdt or pair_style dpd/fdt/energy command to properly initialize the fluctuation-dissipation theorem parameter(s) sigma (and kappa, if necessary).
Note that numerous variants of DPD can be specified by choosing an appropriate combination of the integrator and pair_style dpd/fdt command. DPD under isothermal conditions can be specified by using fix shardlow, fix nve and pair_style dpd/fdt. DPD under isoenergetic conditions can be specified by using fix shardlow, fix nve and pair_style dpd/fdt/energy. DPD under isobaric conditions can be specified by using fix shardlow, fix nph and pair_style dpd/fdt. DPD under isoenthalpic conditions can be specified by using fix shardlow, fix nph and pair_style dpd/fdt/energy. Examples of each DPD variant are provided in the examples/USER/dpd directory.
Restrictions¶
This fix is only available if LAMMPS is built with the USER-DPD package. See the Making LAMMPS section for more info.
This fix is currently limited to orthogonal simulation cell geometries.
This fix must be used with an additional fix that specifies time integration, e.g. fix nve or fix nph.
The Shardlow splitting algorithm requires the sizes of the sub-domain lengths to be larger than twice the cutoff+skin. Generally, the domain decomposition is dependant on the number of processors requested.