Predictive GW calculations using plane waves and pseudopotentials

Abstract

We show that quasiparticle (QP) energies as calculated in the $GW$ approximation converge to the wrong value using the projector augmented wave (PAW) method, since the overlap integrals between occupied orbitals and high energy, plane wave like orbitals, are incorrectly described. The error is shown to be related to the incompleteness of the partial wave basis set inside the atomic spheres. It can be avoided by adopting norm-conserving partial waves, as shown by analytic expressions for the contribution from unoccupied orbitals with high kinetic energy. Furthermore, $G_0W_0$ results based on norm-conserving PAW potentials are presented for a large set of semiconductors and insulators. Accurate extrapolation procedures to the infinite basis set limit and infinite k-point limit are discussed in detail.