Spectral representation analysis of dielectric screening in solids and molecules

Abstract

We propose a new approach to identifying and rationalizing the contribution of core electron polarization to dielectric screening, based on ab initio calculations of the dielectric matrix in its eigenpotential basis. We also present calculations of phonon frequencies, dielectric constants, and quasiparticle energies of several systems, and we discuss the quantitative effect of including core polarization. Our findings illustrate efficient ways of approximating the spectral decomposition of dielectric matrices used, e.g., in many-body perturbation theory and dielectric constant calculations, with substantial computational gains for large systems composed of heavy atoms.