Electronic structure and plasma excitations at the surface of small voids in jellium

Calculation of the electronic structure and plasma excitations at the surfaces of microscopic voids in a metal are reported. The electronic structure is computed using a jellium model for the conduction electrons of a metal and the local-density-functional formalism. The excitation of this electronic system is treated by using a truncated (‘‘long-wavelength’’) version of the random-phase approximation. The surface plasma excitations are a prominent feature of the electron-energy-loss spectra of rare-gas bubbles in aluminum and, hence, an understanding of these excitations can aid in the characteristics of the gas-filled voids that form in irradiated metals. Our calculations are for voids with radii of 4, 7, 14, and 20 a.u. and metallic densities with $r_s$=2, 4, and 6 a.u.