Phonon dispersion relation in rhodium:Ab initiocalculations and neutron- scattering investigations

The phonon dispersion relation in face-centered-cubic rhodium has been investigated by ab initio local-density functional (LDF) calculations and inelastic neutron-scattering measurements. The LDF calculations have been performed both using ultrasoft pseudopotentials and a plane-wave basis and norm-conserving pseudopotentials and a mixed basis set and include also all-electron calculations at a few high-symmetry points. Theory predicts the existence of Kohn anomalies that can be interpreted in terms of the calculated Fermi surfaces. The neutron-scattering experiments confirm that the ab initio calculations are accurate to within 3% (including the position and amplitude of the anomalies).