Kohn anomaly in metastable fcc lanthanum at low temperatures

Inelastic neutron scattering experiments on a single crystal of the metastable fcc phase of lanthanum metal reveal a pronounced temperature dependent anomaly in the tranverse [111] branch of the phonon dispersion curves. A first principles band structure calculation yields a Fermi surface with a nesting feature along the [111] direction and a peak in the bare susceptibility at the same wave vector as the observed experimental anomaly. The calculation differs from previous studies by excluding the 4f states. 7 references