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<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/eff command
</H3>
<P><B>Syntax:</B>
</P>
<PRE>compute ID group-ID ke/eff
</PRE>
<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
<LI>ke/eff = style name of this compute command
</UL>
<P><B>Examples:</B>
</P>
<PRE>compute 1 all ke/eff
</PRE>
<P><B>Description:</B>
</P>
<P>Define a computation that calculates the kinetic energy of motion of a
group of eFF particles (nuclei and electrons), as 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 and the
kinetic energy for each electron is computed as 1/2(me v^2 + 3/4 me
s^2), where m corresponds to the nuclear mass, me to the electron
mass, v to the translational velocity of each particle, and s to the
radial velocity of the electron, 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" and "radial" (only for electrons) 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 degree of freedom. For
the eFF temperature computation via the <A HREF = "compute_temp_eff.html">compute
temp_eff</A> command, these are the same. But
different computes that calculate temperature can subtract out
different non-thermal components of velocity and/or include other
degrees of freedom.
</P>
<P>IMPRORTANT NOTE: The temperature in eFF models 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>See <A HREF = "compute_temp_eff.html">compute temp/eff</A>.
</P>
<P><B>Output info:</B>
</P>
<P>This compute calculates a global scalar (the KE). This value can be
used by any command that uses a global scalar value from a compute as
input. See <A HREF = "Section_howto.html#howto_15">Section_howto 15</A> for an
overview of LAMMPS output options.
</P>
<P>The scalar value calculated by this compute is "extensive". The
scalar value 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> none
</P>
<P><B>Default:</B> none
</P>
</HTML>
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