Plasmon excitation in beryllium: inelastic X-ray scattering experiments and first-principles calculations

G. TIRAO; G. STUTZ; V. SILKIN; E.V. CHULKOV; C. CUSATIS

JOURNAL OF PHYSICS CONDENSED MATTER

INSTITUTE OF PHYSICS PUBLISHING

Lugar: INGLATERRA; Año: 2007 vol. 19 p. 46207 - 46218

0953-8984

An experimental and theoretical study of collective electronic excitations in Beis presented. The plasmon energy and linewidth were measured by means ofinelastic x-ray scattering spectroscopy. Measurements were performed on apolycrystalline sample and in a broad range of momentum transfers within theplasmon excitation regime. Theoretical plasmon dispersion and its linewidth inthe whole Brillouin zone were derived from ab initio evaluations of the electrondensity response function. The calculations were performed with full inclusionof the electron band structure within the random-phase approximation. Goodagreement of experimental plasmon energy and linewidth dispersions withdirection-averaged theoretical results in all investigated q-range is obtained.We conclude that, in Be, the band structure effects alone can account for theobserved finite plasmon lifetime at q = 0, as well as for the linewidth dispersionin the long-wavelength domain.