lammps/doc/compute_ackland_atom.txt

"LAMMPS WWW Site"_lws - "LAMMPS Documentation"_ld - "LAMMPS Commands"_lc :c

:link(lws,http://lammps.sandia.gov)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)

:line

compute ackland/atom command :h3

[Syntax:]

compute ID group-ID ackland/atom :pre

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

[Examples:]

compute 1 all ackland/atom :pre

[Description:]

Defines a computation that calculates the local lattice structure
according to the formulation given in "(Ackland)"_#Ackland.

In contrast to the "centro-symmetry
parameter"_compute_centro_atom.html this method is stable against
temperature boost, because it is based not on the distance between
particles but the angles.  Therefore statistical fluctuations are
averaged out a little more.  A comparison with the Common Neighbor
Analysis metric is made in the paper.

The result is a number which is mapped to the following different
lattice structures:

0 = UNKNOWN
1 = BCC
2 = FCC
3 = HCP
4 = ICO :ul

The neighbor list needed to compute this quantity is constructed each
time the calculation is performed (i.e. 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 of
which computes this quantity.-

[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:]

This compute is part of the "user-ackland" package.  It is only
enabled if LAMMPS was built with that package.  See the "Making
LAMMPS"_Section_start.html#2_3 section for more info.

[Related commands:]

"compute centro/atom"_compute_centro_atom.html

[Default:] none

:line

:link(Ackland)
[(Ackland)] Ackland, Jones, Phys Rev B, 73, 054104 (2006).