Lattice dynamics of CuGeO${}_3$ : inelastic neutron scattering and model calculations

The lattice dynamics in CuGeO${}_3$ has been analyzed by the combination of inelastic neutron scattering studies and lattice dynamical model calculations. We report an almost complete set of dispersion curves along the three orthorhombic directions and along [101]. The dispersion of branches associated with the modes directly involved in the spin-Peierls transition allows to explain the particular propagation vector of the structural distortion in the dimerized phase.