dynamical_matrix command

Syntax

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

group-ID = ID of group of atoms to displace
style = regular or eskm
gamma = finite different displacement length (distance units)

one or more keyword/arg pairs may be appended

keyword = file or binary
  file name = name of output file for the dynamical matrix
  binary arg = yes or no or gzip

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

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 doc page for more info.

Default

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