Many-body effects in electron spectroscopies from absorbates

Abstract

The density-density correlation function and the one-electron Green function of the one-impurity Anderson Hamiltonian are found by the lattice configuration approach, a modification of the resolvent method, recently proposed by the authors. In this approach, the matrix elements of the resolvent operator, R( z) = ( z − H) −1, between suitably chosen many-electron sttes of N, N + 1 or N − 1 particles are put in correspondence with the sites of a rectangular lattice. The chosen many-electron states (configurations) diagonalize H in the absence of hopping ( V = 0) and contain the full intra-atomic correlation ( U) in the doubly-occupied configurations. It turns out that matrix elements between highly-excited configurations, with many electron-hole pairs, can be expressed in terms of matrix elements without electron-hole pairs. This allows doing the calculation by solving a self-consistency matrix equation in a highly reduced basis. The calculated spectral densities are in good agreement with energy-loss, photoemission and inverse photoemission spectra of hydrogen adsorbed on nickel.