Ionization energies of hydrogen-bonded dimers with the outer-valence Green’s function method

Abstract We investigate the accuracy of the Outer-Valence Green’s Function (OVGF) electron propagator approach for the computation of vertical ionization energies (IEs) of several hydrogen-bonded dimers. The vertical IEs were computed with 10 different basis sets (i.e. Pople, correlation-consistent and augmented correlation-consistent) and compared with references obtained at the extrapolated equation-of-motion coupled-cluster singles and doubles level. Our study shows that the OVGF method predicts accurately the IEs of hydrogen-bonded clusters. Furthermore, the choice of an optimal basis set is analyzed: our results suggest that the aug-cc-pVDZ basis set provides the best compromise between accuracy and computational costs. The benchmark study provided in this work represents an essential step to investigate molecular ionization, and thus molecular reduction-oxidation properties, in the liquid phase.