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rLAMMPS lammps
compute_ke_atom_eff.html
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<HTML>
<CENTER><A
HREF =
"http://lammps.sandia.gov"
>
LAMMPS WWW Site
</A>
-
<A
HREF =
"Manual.html"
>
LAMMPS Documentation
</A>
-
<A
HREF =
"Section_commands.html#comm"
>
LAMMPS Commands
</A>
</CENTER>
<HR>
<H3>
compute ke/atom/eff command
</H3>
<P><B>
Syntax:
</B>
</P>
<PRE>
compute ID group-ID ke/atom/eff
</PRE>
<UL><LI>
ID, group-ID are documented in
<A
HREF =
"compute.html"
>
compute
</A>
command
<LI>
ke/atom/eff = style name of this compute command
</UL>
<P><B>
Examples:
</B>
</P>
<PRE>
compute 1 all ke/atom/eff
</PRE>
<P><B>
Description:
</B>
</P>
<P>
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
<A
HREF =
"pair_eff.html"
>
electronic force field
</A>
.
</P>
<P>
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.
</P>
<P>
There is a subtle difference between the quantity calculated by this
compute and the kinetic energy calculated by the
<I>
ke
</I>
or
<I>
etotal
</I>
keyword used in thermodynamic output, as specified by the
<A
HREF =
"thermo_style.html"
>
thermo_style
</A>
command. For this compute, kinetic
energy is "translational" plus electronic "radial" kinetic energy,
calculated by the simple formula above. For thermodynamic output, the
<I>
ke
</I>
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.
</P>
<P>
IMPORTANT NOTE: The temperature in eFF should be monitored via the
<A
HREF =
"compute_temp_eff.html"
>
compute temp/eff
</A>
command, which can be printed
with thermodynamic output by using the
<A
HREF =
"thermo_modify.html"
>
thermo_modify
</A>
command, as shown in the following
example:
</P>
<PRE>
compute effTemp all temp/eff
thermo_style custom step etotal pe ke temp press
thermo_modify temp effTemp
</PRE>
<P>
The value of the kinetic energy will be 0.0 for atoms (nuclei or
electrons) not in the specified compute group.
</P>
<P><B>
Output info:
</B>
</P>
<P>
This compute calculates a scalar quantity for each atom, which can be
accessed by any command that uses per-atom computes as input. See
<A
HREF =
"Section_howto.html#howto_15"
>
Section_howto 15
</A>
for an overview of
LAMMPS output options.
</P>
<P>
The per-atom vector values will be in energy
<A
HREF =
"units.html"
>
units
</A>
.
</P>
<P><B>
Restrictions:
</B>
</P>
<P>
This compute is part of the USER-EFF package. It is only enabled if
LAMMPS was built with that package. See the
<A
HREF =
"Section_start.html#start_3"
>
Making
LAMMPS
</A>
section for more info.
</P>
<P><B>
Related commands:
</B>
</P>
<P><A
HREF =
"dump.html"
>
dump custom
</A>
</P>
<P><B>
Default:
</B>
none
</P>
</HTML>
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