Quasiparticle energies of the uniform electron gas

The uniform electron gas (UEG) model is the simplest model of a metal, a large volume of electrons subject to a uniform background of positive charge. Existing parametrizations of the UEG correlation energy allow us to perform calculations in Kohn-Sham density functional theory (KS-DFT). While the Kohn-Sham and generalized Kohn-Sham orbital energy eigenvalues are not single-particle excitation energies [1,2], how well do they predict the occupied bandwidth of the uniform electron gas or of alkali metals like Na? In this work, we aim to answer this question using the local spin density approximation (LSDA), the Perdew-Burke-Ernzerhof generalized gradient approximation (PBE GGA), and the PBE0 hybrid functional (with 25% of Hartree-Fock exchange). We benchmark our DFT values against the results of higher-level theories and experiment.




[1] E. Jensen and E.W. Plummer, Phys. Rev. Lett. 55, 1918 (1985).
[2] J. E . Northrup, M. S. Hybertsen, and S. G. Louie, Phys. Rev. Lett. 59, 819 (1987).