forked from lijiext/lammps
88 lines
3.2 KiB
HTML
88 lines
3.2 KiB
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 temp/drude 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 temp/drude
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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>temp/drude = 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 TDRUDE all temp/drude
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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 temperatures of core-Drude
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pairs. This compute is designed to be used with the thermalized Drude
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oscillator model. This compute is designed to be used with the
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<A HREF = "tutorial_drude.html">thermalized Drude oscillator model</A>. Polarizable
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models in LAMMPS are described in <A HREF = "Section_howto.html#howto_25">this
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Section</A>.
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</P>
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<P>Drude oscillators consist of a core particle and a Drude particle
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connected by a harmonic bond, and the relative motion of these Drude
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oscillators is usually maintained cold by a specific thermostat that
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acts on the relative motion of the core-Drude particle
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pairs. Therefore, because LAMMPS considers Drude particles as normal
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atoms in its default temperature compute (<A HREF = "compute_temp.html">compute
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temp</A> command), the reduced temperature of the
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core-Drude particle pairs is not calculated correctly.
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</P>
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<P>By contrast, this compute calculates the temperature of the cores
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using center-of-mass velocities of the core-Drude pairs, and the
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reduced temperature of the Drude particles using the relative
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velocities of the Drude particles with respect to their cores.
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Non-polarizable atoms are considered as cores. Their velocities
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contribute to the temperature of the cores.
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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 temperature) and a global
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vector of length 6, which can be accessed by indices 1-6, whose components
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are
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</P>
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<OL><LI>temperature of the centers of mass (temperature units)
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<LI>temperature of the dipoles (temperature units)
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<LI>number of degrees of freedom of the centers of mass
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<LI>number of degrees of freedom of the dipoles
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<LI>kinetic energy of the centers of mass (energy units)
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<LI>kinetic energy of the dipoles (energy units)
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</OL>
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<P>These values can be used by any command that uses global scalar or
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vector values from a compute as input. See <A HREF = "Section_howto.html#howto_15">this
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section</A> for an overview of LAMMPS output
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options.
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</P>
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<P>Both the scalar value and the first two values of the vector
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calculated by this compute are "intensive". The other 4 vector values
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are "extensive".
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</P>
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<P><B>Restrictions:</B>
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</P>
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<P>The number of degrees of freedom contributing to the temperature is
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assumed to be constant for the duration of the run unless the
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<I>fix_modify</I> command sets the option <I>dynamic yes</I>.
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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 = "fix_drude.html">fix drude</A>, <A HREF = "fix_langevin_drude.html">fix
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langevin_drude</A>, <A HREF = "fix_drude_transform.html">fix
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drude/transform</A>, <A HREF = "pair_thole.html">pair_style
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thole</A>, <A HREF = "compute_temp.html">compute temp</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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