First principlesT-matrix calculations for Auger spectra of hydrocarbon systems

Abstract

Auger spectra of hydrocarbon systems ($\mathrm{C}{\mathrm{H}}_{4}$, ${\mathrm{C}}_{2}{\mathrm{H}}_{2}$, ${\mathrm{C}}_{2}{\mathrm{H}}_{4}$, and ${\mathrm{C}}_{6}{\mathrm{H}}_{6}$ molecules) are calculated from the first principles using Green's function method based on the many-body perturbation theory beyond the framework of the density functional theory. The ladder approximation to the two-particle Green's function ($T$ matrix), which describes the short-range electron correlations between two holes or electrons, can accurately determine in a single calculation the whole spectrum of doubly ionized final states of the Auger process. The two-particle eigenvalues and eigenfunctions are determined from the Bethe-Salpeter equation for the $T$ matrix. The obtained results are in good agreement with the experimental data.