Importance of reference Hamiltonians containing exact exchange for accurate one-shotGWcalculations of Cu2O

Abstract

We show that a ``one-shot'' $GW$ approach (denoted ${G}_{0}$${W}_{0}$) can accurately calculate the photoemission/inverse-photoemission properties of Cu${}_{2}$O. As the results of any perturbative method are heavily dependent on the reference state, the appropriate reference Hamiltonian for ${G}_{0}$${W}_{0}$ is identified by evaluating the performance of density-functional-theory-based input wave functions and eigenvalues generated with selected exchange-correlation functionals. It is shown that a reference Hamiltonian employing the hybrid Heyd-Scuseria-Ernzerhof functional used in conjunction with ${G}_{0}$${W}_{0}$ produces an accurate photoemission/inverse-photoemission band gap and photoemission spectrum whose character is then further analyzed. The physical origin of why a hybrid functional is required for the zeroth-order wave function is discussed, giving insight into the unique electronic structure of Cu${}_{2}$O in comparison to other transition-metal oxides.