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

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

:line

dynamical_matrix command :h3

[Syntax:]

dynamical_matrix group-ID style gamma args keyword value ... :pre

group-ID = ID of group of atoms to displace :ulb,l
style = {regular} or {eskm} :l
gamma = finite different displacement length (distance units) :l
one or more keyword/arg pairs may be appended :l
  keyword = {file} or {binary}
    {file} name = name of output file for the dynamical matrix
    {binary} arg = {yes} or {no} or {gzip} :pre
:ule

[Examples:]

dynamical_matrix 1 regular 0.000001
dynamical_matrix 1 eskm 0.000001
dynamical_matrix 3 regular 0.00004 file dynmat.dat
dynamical_matrix 5 eskm 0.00000001 file dynamical.dat binary yes :pre

[Description:]

Calculate the dynamical matrix of the selected group.

[Restrictions:]

The command collects the entire dynamical matrix a single MPI rank,
so the memory requirements can be very significant for large systems.

This command assumes a periodic system.

This command is part of the USER-PHONON package.  It is only enabled if
LAMMPS was built with that package.  See the "Build
package"_Build_package.html doc page for more info.

[Related commands:]

"fix phonon"_fix_phonon.html

"compute hma"_compute_hma.html uses an analytic formulation of the hessian
provided by Pair's single_hessian.

[Default:]

The default settings are file = "dynmat.dyn", binary = no
