dynamical matrix calculation

There is a user-package called fix-phonon in LAMMPS.
(http://code.google.com/p/fix-phonon/). One need to install this package
before building LAMMPS. There are examples given and also the
documentation which tells you how to use it to calculate the dynamical
matrix, phonon dispersion curve etc..

I have used it to get phonon dispersion and map out soft phonon modes for
a model system of colloids with complex interactions. Now I want to
calculate the eigenvectors of the dynamical matrix to get the particle
displacements. For that I calculated the dynamical matrix at a q-value
where I am getting the soft modes. But, as I mentioned before, I don't
understand why it is a 4by8 matrix in stead of a 4by4 matrix. Do anybody
have any idea?


Agreed - so if someone has such a package, please let