forked from lijiext/lammps
70 lines
2.3 KiB
Plaintext
70 lines
2.3 KiB
Plaintext
"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c
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:link(lws,http://lammps.sandia.gov)
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:link(ld,Manual.html)
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:link(lc,Section_commands.html#comm)
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:line
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compute temp/com command :h3
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[Syntax:]
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compute ID group-ID temp/com :pre
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ID, group-ID are documented in "compute"_compute.html command
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temp/com = style name of this compute command
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[Examples:]
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compute newT oxygen temp/com :pre
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[Description:]
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Define a compute to calculate the temperature of a group of atoms,
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where the momentum of each atom includes that of atoms to which
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it is directly bonded.
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A compute of this style can be used by any command that computes a temperature,
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e.g. "thermo_modify"_thermo_modify.html, "fix
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temp/rescale"_fix_temp_rescale.html, "fix npt"_fix_npt.html, etc.
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The temperature is calculated by the formula KE = dim/2 N k T, where
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KE = total kinetic energy of the group of atoms
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The kinetic energy of each atom is based on the center of mass motion
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of itself and all the atoms directly bonded to it.
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N = number of atoms in the
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group, k = Boltzmann constant, and T = temperature.
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The dim parameter is adjusted to give the correct number of
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degrees of freedom.
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The number of atoms contributing to the temperature is assumed to be
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constant for the duration of the run; use the {dynamic} option of the
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"compute_modify"_compute_modify.html command if this is not the case.
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This command can also be used to compute a vector of two quantities. The
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first is the temperature described above; the second is the temperature
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based on the complementary part of the kinetic energy i.e. it uses the
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momentum of the atom and its directly-bonded neighbors, relative to their
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center of mass. It is scaled by the total number of atoms minus the total
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number of group atoms.
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This compute should only be used in cases where none of the atoms in the group
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have any directly-bonded neighbors in common, including each other.
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If there are no directly-bonded
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neighbors, then this compute is equivalent to "compute temp"
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[Output info:]
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All values calculated by this compute are "intensive",
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meaning they are independent of the number of atoms in the simulation.
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[Restrictions:] none
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[Related commands:]
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"compute temp"_compute_temp.html, "compute
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temp/region"_compute_temp_region.html, "compute
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pressure"_compute_pressure.html
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[Default:] none
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