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lammps/doc/src/fix_nve_sphere.txt
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fix_nve_sphere.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 nve/sphere command :h3
fix nve/sphere/omp command :h3
[Syntax:]
fix ID group-ID nve/sphere :pre
ID, group-ID are documented in "fix"_fix.html command :ulb,l
nve/sphere = style name of this fix command :l
zero or more keyword/value pairs may be appended :l
keyword = {update}
{update} value = {dipole} or {dipole/dlm}
dipole = update orientation of dipole moment during integration
dipole/dlm = use DLM integrator to update dipole orientation :pre
:ule
[Examples:]
fix 1 all nve/sphere
fix 1 all nve/sphere update dipole
fix 1 all nve/sphere update dipole/dlm :pre
[Description:]
Perform constant NVE integration to update position, velocity, and
angular velocity for finite-size spherical particles in the group each
timestep. V is volume; E is energy. This creates a system trajectory
consistent with the microcanonical ensemble.
This fix differs from the "fix nve"_fix_nve.html command, which
assumes point particles and only updates their position and velocity.
If the {update} keyword is used with the {dipole} value, then the
orientation of the dipole moment of each particle is also updated
during the time integration. This option should be used for models
where a dipole moment is assigned to finite-size particles,
e.g. spheroids via use of the "atom_style hybrid sphere
dipole"_atom_style.html command.
The default dipole orientation integrator can be changed to the
Dullweber-Leimkuhler-McLachlan integration scheme
"(Dullweber)"_#nh-Dullweber when using {update} with the value
{dipole/dlm}. This integrator is symplectic and time-reversible,
giving better energy conservation and allows slightly longer timesteps
at only a small additional computational cost.
:line
Styles with a {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 "Section_accelerate"_Section_accelerate.html
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 GPU, USER-INTEL, KOKKOS,
USER-OMP and OPT packages, respectively. They are only enabled if
LAMMPS was built with those packages. See the "Making
LAMMPS"_Section_start.html#start_3 section for more info.
You can specify the accelerated styles explicitly in your input script
by including their suffix, or you can use the "-suffix command-line
switch"_Section_start.html#start_7 when you invoke LAMMPS, or you can
use the "suffix"_suffix.html command in your input script.
See "Section_accelerate"_Section_accelerate.html of the manual for
more instructions on how to use the accelerated styles effectively.
: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 requires that atoms store torque and angular velocity (omega)
and a radius as defined by the "atom_style sphere"_atom_style.html
command. If the {dipole} keyword is used, then they must also store a
dipole moment as defined by the "atom_style dipole"_atom_style.html
command.
All particles in the group must be finite-size spheres. They cannot
be point particles.
[Related commands:]
"fix nve"_fix_nve.html, "fix nve/asphere"_fix_nve_asphere.html
[Default:] none
:line
:link(nve-Dullweber)
[(Dullweber)] Dullweber, Leimkuhler and McLachlan, J Chem Phys, 107,
5840 (1997).
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