title: Plasmons in sodium under pressure: increasing departure from nearly free-electron behavior.
abstract: We have measured plasmon energies in Na under high pressure up to 43 GPa using inelastic x-ray scattering (IXS). The momentum-resolved results show clear deviations, growing with increasing pressure, from the predictions for a nearly free-electron metal. Plasmon energy calculations based on first-principles electronic band structures and a quasiclassical plasmon model allow us to identify a pressure-induced increase in the electron-ion interaction and associated changes in the electronic band structure as the origin of these deviations, rather than effects of exchange and correlation. Additional IXS results obtained for K and Rb are addressed briefly.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany. I.Loa@ed.ac.uk
authors.forename: I
authors.initials: I
authors.lastname: Loa
authors.forename: K
authors.initials: K
authors.lastname: Syassen
authors.forename: G
authors.initials: G
authors.lastname: Monaco
authors.forename: G
authors.initials: G
authors.lastname: Vankó
authors.forename: M
authors.initials: M
authors.lastname: Krisch
authors.forename: M
authors.initials: M
authors.lastname: Hanfland