forked from lijiext/lammps
65 lines
2.1 KiB
HTML
65 lines
2.1 KiB
HTML
<HTML>
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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>
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</CENTER>
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<HR>
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<H3>compute ke command
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</H3>
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<P><B>Syntax:</B>
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</P>
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<PRE>compute ID group-ID ke
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</PRE>
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<UL><LI>ID, group-ID are documented in <A HREF = "compute.html">compute</A> command
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<LI>ke = style name of this compute command
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</UL>
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<P><B>Examples:</B>
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</P>
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<PRE>compute 1 all ke
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</PRE>
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<P><B>Description:</B>
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</P>
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<P>Define a computation that calculates the translational kinetic energy
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of a group of particles.
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</P>
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<P>The kinetic energy or each particle is computed as 1/2 m v^2, where m
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and v are the mass and velocity of the particle.
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</P>
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<P>There is a subtle difference between the quantity calculated by this
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compute and the kinetic energy calculated by the <I>ke</I> or <I>etotal</I>
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keyword used in thermodynamic output, as specified by the
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<A HREF = "thermo_style.html">thermo_style</A> command. For this compute, kinetic
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energy is "translational" kinetic energy, calculated by the simple
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formula above. For thermodynamic output, the <I>ke</I> keyword infers
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kinetic energy from the temperature of the system with 1/2 Kb T of
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energy for each degree of freedom. For the default temperature
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computation via the <A HREF = "compute_temp.html">compute temp</A> command, these
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are the same. But different computes that calculate temperature can
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subtract out different non-thermal components of velocity and/or
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include different degrees of freedom (translational, rotational, etc).
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</P>
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<P><B>Output info:</B>
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</P>
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<P>This compute calculates a global scalar (the KE). This value can be
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used by any command that uses a global scalar value from a compute as
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input. See <A HREF = "Section_howto.html#4_15">this section</A> for an overview of
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LAMMPS output options.
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</P>
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<P>The scalar value calculated by this compute is "extensive". The
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scalar value will be in energy <A HREF = "units.html">units</A>.
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</P>
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<P><B>Restrictions:</B> none
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</P>
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<P><B>Related commands:</B>
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</P>
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<P><A HREF = "compute_erotate_sphere.html">compute erotate/sphere</A>
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</P>
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<P><B>Default:</B> none
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</P>
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</HTML>
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