title: First-principles calculations of quasiparticle excitations of open-shell condensed matter systems.
abstract: We develop a Green's function approach to quasiparticle excitations of open-shell systems within the GW approximation. It is shown that accurate calculations of the characteristic multiplet structure require a precise knowledge of the self-energy and, in particular, its poles. We achieve this by constructing the self-energy from appropriately chosen mean-field theories on a fine frequency grid. We apply our method to a two-site Hubbard model, several molecules, and the negatively charged nitrogen-vacancy defect in diamond and obtain good agreement with experiment and other high-level theories.
authors.affiliation: Department of Physics, University of California, Berkeley, California 94720, USA.
authors.forename: Johannes
authors.initials: J
authors.lastname: Lischner
authors.forename: Jack
authors.initials: J
authors.lastname: Deslippe
authors.forename: Manish
authors.initials: M
authors.lastname: Jain
authors.forename: Steven G
authors.initials: SG
authors.lastname: Louie