X-ray absorption of liquid water by advanced ab initio methods

Abstract

© 2017 American Physical Society. Oxygen K-edge x-ray absorption spectra of liquid water are computed based on configurations from advanced ab initio molecular dynamics simulations, as well as an electron excitation theory from the GW method. One the one hand, the molecular structures of liquid water are accurately predicted by including both van der Waals interactions and a hybrid functional (PBE0). On the other hand, the dynamic screening effects on electron excitation are approximately described by the recently developed enhanced static Coulomb-hole and screened-exchange approximation of W. Kang and M. S. Hybertsen [Phys. Rev. B 82, 195108 (2010)PRBMDO1098-012110.1103/PhysRevB.82.195108]. The resulting spectra of liquid water are in better quantitative agreement with the experimental spectra due to the softened hydrogen bonds and the slightly broadened spectra originating from the better screening model.