forked from lijiext/lammps
61 lines
1.9 KiB
Plaintext
61 lines
1.9 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 vcm/molecule command :h3
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[Syntax:]
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compute ID group-ID vcm/molecule :pre
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ID, group-ID are documented in "compute"_compute.html command
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vcm/molecule = style name of this compute command :ul
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[Examples:]
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compute 1 fluid vcm/molecule :pre
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[Description:]
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Define a computation that calculates the center-of-mass velocity of
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individual molecules. The x,y,z components of the velocity of each
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molecule are computed. This is calcualted by summing mass*velocity
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for each atom in the molecule and dividing the sum by the total mass
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of the molecule.
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The velocity of a particular molecule is only computed if one or more
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of its atoms are in the specified group. Normally all atoms in the
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molecule should be in the group, however this is not required. LAMMPS
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will warn you if this is not the case. Only atoms in the group
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contribute to the velocity calculation for the molecule.
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The ordering of per-molecule quantities produced by this compute is
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consistent with the ordering produced by other compute commands that
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generate per-molecule datums. Conceptually, them molecule IDs will be
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in ascending order for any molecule with one or more of its atoms in
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the specified group.
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[Output info:]
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This compute calculates a global array where the number of rows =
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Nmolecules and the number of columns = 3 for the vx,vy,vz components
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of the center-of-mass velocity of each molecule. These values can be
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accessed by any command that uses global array values from a compute
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as input. See "Section_howto 15"_Section_howto.html#howto_15 for an
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overview of LAMMPS output options.
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The array values are "intensive". The array values will be in
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distance "units"_units.html.
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[Restrictions:] none
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[Related commands:]
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"compute atom/molecule"_compute_atom_molecule.html
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[Default:] none
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