forked from lijiext/lammps
64 lines
1.8 KiB
Plaintext
64 lines
1.8 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 gyration command :h3
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[Syntax:]
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compute ID group-ID gyration :pre
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ID, group-ID are documented in "compute"_compute.html command
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gyration = style name of this compute command :ul
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[Examples:]
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compute 1 molecule gyration :pre
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[Description:]
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Define a computation that calculates the radius of gyration Rg of the
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group of atoms, including all effects due to atoms passing thru
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periodic boundaries.
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Rg is a measure of the size of the group of atoms, and is computed by
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this formula
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:c,image(Eqs/compute_gyration.jpg)
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where M is the total mass of the group, Rcm is the center-of-mass
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position of the group, and the sum is over all atoms in the group.
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IMPORTANT NOTE: The coordinates of an atom contribute to Rg in
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"unwrapped" form, by using the image flags associated with each atom.
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See the "dump custom"_dump.html command for a discussion of
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"unwrapped" coordinates. See the Atoms section of the
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"read_data"_read_data.html command for a discussion of image flags and
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how they are set for each atom. You can reset the image flags
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(e.g. to 0) before invoking this compute by using the "set
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image"_set.html command.
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[Output info:]
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This compute calculates a global scalar (Rg). This value can be used
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by any command that uses a global scalar value from a compute as
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input. See "this section"_Section_howto.html#4_15 for an overview of
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LAMMPS output options.
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The scalar value calculated by this compute is "intensive", meaning it
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is independent of the number of atoms in the simulation.
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The scalar value will be in distance "units"_units.html.
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[Restrictions:] none
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[Related commands:]
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"compute gyration/molecule"_compute_gyration_molecule.html
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[Default:] none
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