Dielectric anisotropy in the GW space-time method

Excited-state calculations, notably for quasiparticle band structures, are nowadays routinely performed within the GW approximation for the electronic self-energy. Nevertheless, certain numerical approximations and simplifications are still employed in practice to make the computations feasible. An important aspect for periodic systems is the proper treatment of the singularity of the screened Coulomb interaction in reciprocal space, which results from the slow 1/r decay in real space. This must be done without introducing artificial interactions between the quasiparticles and their periodic images in repeated cells, which occur when integrals of the screened Coulomb interaction are discretised in reciprocal space. An adequate treatment of both aspects is crucial for a numerically stable computation of the self-energy. In this article we build on existing schemes for isotropic screening and present an extension for anisotropic systems. We also show how the contributions to the diele...

• Type: Journal
• Year: 2007
• Where: CPHYSICS
• Authors: Christoph Freysoldt, Philipp Eggert, Patrick Rinke, Arno Schindlmayr, R. W. Godby, Matthias Scheffler
• Keywords: Certain Numerical Approximations, Coulomb Interaction, CPHYSICS 2007, Reciprocal Space