GW approximation for open-shell molecules: a first-principles study

A prerequisite to characterize magnetic materials is the capability describe systems containing unpaired electrons. In this study, we benchmark one-shot GW (G0W0) on top of different unrestricted mean-field solutions for open-shell molecules using Dunning's correlation-consistent basis sets expanded in terms Gaussian functions. We find that G0W0 correction hybrid functionals provides reasonably accurate results ionization energies when compared those obtained from high-level ab initio methods. Moreover, quality exchange–correlation approximation evaluated by discrepancy between energy neutral and electron affinity corresponding cations. Furthermore, assess reproduce correct ordering molecular spin–orbitals. To such an aim, thoroughly discuss three CN, NH2, O2, which approximate fail correctly capture single-electron spectrum. Particularly, demonstrate overestimation exchange studied spin–orbitals reduced dynamic correlation term, restoring orbital ordering. Interestingly, deviations energies, comparison with our reference, can be very orbitals symmetry, e.g. ? ?-type orbitals.