Approximate spectral decomposition of density-density response functions*

Recently, an implementation of the G₀W₀ method that does not require any explicit summation over empty electronic states has been proposed. The implementation uses a spectral decomposition of density-density response functions [1]. To accelerate many body perturbation theory calculations, we propose a method to obtain approximate spectral decompositions of density-density response functions, which do not compromise the accuracy of quasi-particle energies obtained in G₀W₀ calculations. The performance of this approximation for molecules, solids and heterogeneous interfaces will be discussed.

[1] H. F. Wilson, et al. Phys. Rev. B 2008; H. F. Wilson, et al. Phys. Rev. B 2009; T. A. Pham, et al. Phys. Rev. B 2013