title: The hydrogen bond in ice probed by soft x-ray spectroscopy and density functional theory.
abstract: We combine photoelectron and x-ray absorption spectroscopy with density functional theory to derive a molecular orbital picture of the hydrogen bond in ice. We find that the hydrogen bond involves donation and back-donation of charge between the oxygen lone pair and the O-H antibonding orbitals on neighboring molecules. Together with internal s-p rehybridization this minimizes the repulsive charge overlap of the connecting oxygen and hydrogen atoms, which is essential for a strong attractive electrostatic interaction. Our joint experimental and theoretical results demonstrate that an electrostatic model based on only charge induction from the surrounding medium fails to properly describe the internal charge redistributions upon hydrogen bonding.
authors.affiliation: Stanford Synchrotron Radiation Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA. nilsson@slac.stanford.edu
authors.forename: A
authors.initials: A
authors.lastname: Nilsson
authors.forename: H
authors.initials: H
authors.lastname: Ogasawara
authors.forename: M
authors.initials: M
authors.lastname: Cavalleri
authors.forename: D
authors.initials: D
authors.lastname: Nordlund
authors.forename: M
authors.initials: M
authors.lastname: Nyberg
authors.forename: Ph
authors.initials: P
authors.lastname: Wernet
authors.forename: L G M
authors.initials: LG
authors.lastname: Pettersson