Electron binding energies of water clusters: Implications for the electronic properties of liquid water

Green’s function (GF) calculations for the valence electron binding energies of water clusters (H2O)2−8 are reported. The results are compared with experiment for H2O and (H2O)2, and with Hartree–Fock and Kohn–Sham calculations with an exchange-correlation functional parametrized to reproduce electronic properties of the dimer. For the liquid, sequential Monte Carlo/GF calculations lead to estimates of the outermost electron binding energy (11.59 ± 0.12 eV) and of the water conduction band edge (V0) as −0.79 ± 0.08 eV. Our predictions agree with experimental and recent theoretical results and support that the water electron affinity (−V0) is smaller than the typical literature value (1.2 eV).