Ab initio calculations of the dynamic response of beryllium

Correlation-induced double-plasmon excitation in simple metals studied by inelastic x-ray scattering

We report a new type of peaklike structure observed in the tail of the dynamic structure factor of simple metals, measured by inelastic x-ray scattering. Based on the momentum-transfer dependence of the energy position and the intensity of this structure, it has been unambiguously attributed to intrinsic plasmon-plasmon excitations, an electronic correlation effect that was theoretically predicted by many-body perturbation theory of the homogeneous-electron-gas model beyond the random-phase approximation. This signature appears to be largely unaffected by electron-ion interaction effects. Thus a structure that is primarily caused by correlation effects in the electron gas has been found experimentally in the dynamic structure factor of simple metals.

Band structure versus dynamical exchange-correlation effects in surface plasmon energy and damping: a first-principles calculation

A first-principles parameter-free calculation that includes full three-dimensional band structure and dynamical exchange correlations is reported for the dynamical surface response and surface plasmon (SP) on a simple metal prototype surface Mg(0001). We demonstrate that band structure effects have a more profound impact on the SP characteristics than dynamical exchange correlations. A comparison with jellium and one-dimensional potential evaluations shows that the band structure is of paramount importance for the correct description of the SP linewidth and also leads to a better description of the SP energy dispersion. The inclusion of the exchange-correlation kernel results in a better agreement with experimental data. We show that lateral crystal local field effects have a negligible impact on the SP properties. Significant anisotropy is predicted for the SP linewidth.