[lammps-users] Computation of vibrational frequencies

please always keep the list in cc.

I want to compute a Hessian (matrix of second derivatives of potential
energy with respect to coordinates) of a system and its eigenvalues.

ok. that is not implemented directly, but
you should be able to do most of the work
via finite differences through some smart
scripting using the displace_atoms command
followed by a run 0 to get the energy due
to the displacement and then writing a
small script to postprocess the resulting
potential energies into a matrix and
diagonalize it.

i hope you don't want to do this for
very large systems, or do you?