M.R.Johnson and H.P.Trommsdorff,
Dispersion of vibrational modes in benzoic acid crystals
Chem.Phys.Lett., August (2002).
Crystal: Benzoic acid
Space groups: monoclinic P2_1/c (Z=4)
Lattice constants: a=5.393, b=5.003, c=21.689, beta=98.51 deg.
Supercell: monoclinic 2x2x1
Phonon dispersion relations of internal modes in benzoic acid.
These modes are usually considered as dispersionless.