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lammps/doc/src/fix_mvv_dpd.txt
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"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)
:line
fix mvv/dpd command :h3
fix mvv/edpd command :h3
fix mvv/tdpd command :h3
[Syntax:]
fix ID group-ID mvv/dpd lambda :pre
fix ID group-ID mvv/edpd lambda :pre
fix ID group-ID mvv/tdpd lambda :pre
ID, group-ID are documented in "fix"_fix.html command
mvv/dpd, mvv/edpd, mvv/tdpd = style name of this fix command
lambda = (optional) relaxation parameter (unitless) :ul
[Examples:]
fix 1 all mvv/dpd
fix 1 all mvv/dpd 0.5
fix 1 all mvv/edpd
fix 1 all mvv/edpd 0.5
fix 1 all mvv/tdpd
fix 1 all mvv/tdpd 0.5 :pre
[Description:]
Perform time integration using the modified velocity-Verlet (MVV)
algorithm to update position and velocity (fix mvv/dpd), or position,
velocity and temperature (fix mvv/edpd), or position, velocity and
concentration (fix mvv/tdpd) for particles in the group each timestep.
The modified velocity-Verlet (MVV) algorithm aims to improve the
stability of the time integrator by using an extrapolated version of
the velocity for the force evaluation:
:c,image(Eqs/fix_mvv_dpd.jpg)
where the parameter <font size="4">&lambda;</font> depends on the
specific choice of DPD parameters, and needs to be tuned on a
case-by-case basis. Specification of a {lambda} value is opttional.
If specified, the setting must be from 0.0 to 1.0. If not specified,
a default value of 0.5 is used, which effectively reproduces the
standard velocity-Verlet (VV) scheme. For more details, see
"Groot"_#Groot.
Fix {mvv/dpd} updates the position and velocity of each atom. It can
be used with the "pair_style mdpd"_pair_meso.html command or other
pair styles such as "pair dpd"_pair_dpd.html.
Fix {mvv/edpd} updates the per-atom temperature, in addition to
position and velocity, and must be used with the "pair_style
edpd"_pair_meso.html command.
Fix {mvv/tdpd} updates the per-atom chemical concentration, in
addition to position and velocity, and must be used with the
"pair_style tdpd"_pair_meso.html command.
:line
[Restart, fix_modify, output, run start/stop, minimize info:]
No information about this fix is written to "binary restart
files"_restart.html. None of the "fix_modify"_fix_modify.html options
are relevant to this fix. No global or per-atom quantities are stored
by this fix for access by various "output
commands"_Section_howto.html#howto_15. No parameter of this fix can
be used with the {start/stop} keywords of the "run"_run.html command.
This fix is not invoked during "energy minimization"_minimize.html.
[Restrictions:]
This fix is part of the USER-MESO package. It is only enabled if
LAMMPS was built with that package. See the "Making
LAMMPS"_Section_start.html#start_3 section for more info.
[Related commands:]
"pair_style mdpd"_pair_meso.html, "pair_style edpd"_pair_meso.html,
"pair_style tdpd"_pair_meso.html
[Default:]
The default value for the optional {lambda} parameter is 0.5.
:line
:link(Groot)
[(Groot)] Groot and Warren, J Chem Phys, 107: 4423-4435 (1997). DOI:
10.1063/1.474784
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