lammps/doc/compute_centro_atom.txt

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compute centro/atom command :h3

[Syntax:]

compute ID group-ID centro/atom :pre

ID, group-ID are documented in "compute"_compute.html command
centro/atom = style name of this compute command :ul

[Examples:]

compute 1 all centro/atom :pre

[Description:]

Define a computation that calculates the centro-symmetry parameter for
each atom in the group.  In solid-state systems the centro-symmetry
parameter is a useful measure of the local lattice disorder around an
atom and can be used to characterize whether the atom is part of a
perfect lattice, a local defect (e.g. a dislocation or stacking
fault), or at a surface.

The value of the centro-symmetry parameter will be 0.0 for atoms not
in the specified compute group.

This parameter is computed using the following formula from
"(Kelchner)"_#Kelchner

:c,image(Eqs/centro_symmetry.jpg)

where the 12 nearest neighbors are found (for fcc lattices) and Ri and
Ri+6 are the vectors from the central atom to the opposite pair of
nearest neighbors.  Atoms not in the group are included in the 12
neighbors used in this calculation.

The neighbor list needed to compute this quantity is constructed each
time the calculation is performed (e.g. each time a snapshot of atoms
is dumped).  Thus it can be inefficient to compute/dump this quantity
too frequently or to have multiple compute/dump commands, each with a
{centro/atom} style.

[Output info:]

This compute calculates a scalar quantity for each atom, which can be
accessed by any command that uses per-atom values from a compute as
input.  See "this section"_Section_howto.html#4_15 for an overview of
LAMMPS output options.

[Restrictions:] none

[Related commands:]

"compute cna/atom"_compute_cna_atom.html

[Default:] none

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:link(Kelchner)
[(Kelchner)] Kelchner, Plimpton, Hamilton, Phys Rev B, 58, 11085 (1998).