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lammps/doc/src/compute_ke_atom_eff.txt
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compute_ke_atom_eff.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
compute ke/atom/eff command :h3
[Syntax:]
compute ID group-ID ke/atom/eff :pre
ID, group-ID are documented in "compute"_compute.html command
ke/atom/eff = style name of this compute command :ul
[Examples:]
compute 1 all ke/atom/eff :pre
[Description:]
Define a computation that calculates the per-atom translational
(nuclei and electrons) and radial kinetic energy (electron only) in a
group. The particles are assumed to be nuclei and electrons modeled
with the "electronic force field"_pair_eff.html.
The kinetic energy for each nucleus is computed as 1/2 m v^2, where m
corresponds to the corresponding nuclear mass, and the kinetic energy
for each electron is computed as 1/2 (me v^2 + 3/4 me s^2), where me
and v correspond to the mass and translational velocity of each
electron, and s to its radial velocity, respectively.
There is a subtle difference between the quantity calculated by this
compute and the kinetic energy calculated by the {ke} or {etotal}
keyword used in thermodynamic output, as specified by the
"thermo_style"_thermo_style.html command. For this compute, kinetic
energy is "translational" plus electronic "radial" kinetic energy,
calculated by the simple formula above. For thermodynamic output, the
{ke} keyword infers kinetic energy from the temperature of the system
with 1/2 Kb T of energy for each (nuclear-only) degree of freedom in
eFF.
NOTE: The temperature in eFF should be monitored via the "compute
temp/eff"_compute_temp_eff.html command, which can be printed with
thermodynamic output by using the "thermo_modify"_thermo_modify.html
command, as shown in the following example:
compute effTemp all temp/eff
thermo_style custom step etotal pe ke temp press
thermo_modify temp effTemp :pre
The value of the kinetic energy will be 0.0 for atoms (nuclei or
electrons) not in the specified compute group.
[Output info:]
This compute calculates a scalar quantity for each atom, which can be
accessed by any command that uses per-atom computes as input. See
"Section_howto 15"_Section_howto.html#howto_15 for an overview of
LAMMPS output options.
The per-atom vector values will be in energy "units"_units.html.
[Restrictions:]
This compute is part of the USER-EFF 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:]
"dump custom"_dump.html
[Default:] none
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