Ab initio calculation of excitonic effects in realistic materials

Ab initio calculations, based on the density functional theory (DFT) in the local density approximation (LDA), allow for the description of the ground state properties of a wide class of materials. Also one-quasiparticle excitations can be obtained with good precision by adding self-energy corrections to the DFT-LDA eigenvalues. A realistic description of two-particle excitations, like the creation of electron-hole pairs in absorption experiments, is hardly feasible for systems where the electron and the hole interact. In this work we show how such excitonic effects can be included in ab initio electronic structure calculations, via the solution of an effective two-particle equation. Results for different systems are presented. Copyright (C) 1998 Elsevier Science B.V.