Lattice dynamics in copper indium diselenide by inelastic neutron scattering

The phonon dispersion curves along the [100] and [001] directions of CuInSe 2 have been measured by inelastic neutron scattering. The neutron measureme nts reveal the uncertainty of optical measurements because of the large abs orption of this material. The lattice dynamics is analysed with a rigid ion model: Born-von Karman short range interactions associated with long range electrostatic forces. The calculated dispersion curves are in good agreeme nt with the experiment. The atomic displacements associated with each vibra tional mode are used to discuss the optical phonons. The obtained results p rovide a strong experimental basis from which we can validate the ab initio methods.