forked from lijiext/lammps
67 lines
1.9 KiB
Plaintext
67 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 centro/atom command :h3
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[Syntax:]
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compute ID group-ID centro/atom :pre
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ID, group-ID are documented in "compute"_compute.html command
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centro/atom = style name of this compute command :ul
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[Examples:]
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compute 1 all centro/atom :pre
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[Description:]
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Define a computation that calculates the centro-symmetry parameter for
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each atom in a group. In solid-state systems the centro-symmetry
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parameter is a useful measure of the local lattice disorder around an
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atom and can be used to characterize whether the atom is part of a
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perfect lattice, a local defect (e.g. a dislocation or stacking
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fault), or at a surface.
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The value of the centro-symmetry parameter will be 0.0 for atoms not
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in the specified compute group.
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This parameter is computed using the following formula from
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"(Kelchner)"_#Kelchner
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:c,image(Eqs/centro_symmetry.jpg)
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where the 12 nearest neighbors are found and Ri and Ri+6 are the
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vectors from the central atom to the opposite pair of nearest
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neighbors. Atoms not in the group are included in the 12 neighbors
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used in this calculation.
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The neighbor list needed to compute this quantity is constructed each
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time the calculation is performed (i.e. each time a snapshot of atoms
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is dumped). Thus it can be inefficient to compute/dump this quantity
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too frequently or to have multiple compute/dump commands, each of a
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{centro/atom} style.
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[Output info:]
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This compute calculates a scalar quantity for each atom, which can be
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accessed by any command that uses per-atom computes as input. See
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"this section"_Section_howto.html#4_15 for an overview of LAMMPS
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output options.
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[Restrictions:] none
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[Related commands:] none
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[Default:] none
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:line
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:link(Kelchner)
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[(Kelchner)] Kelchner, Plimpton, Hamilton, Phys Rev B, 58, 11085 (1998).
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