title: The changing hydrogen-bond network of water from the bulk to the surface of a cluster: a born-oppenheimer molecular dynamics study.
abstract: The effect of the environment on the properties of water in the bulk and at the surface of a cluster is studied by all-electron Born-Oppenheimer molecular dynamics. The vibrational spectrum of surface and bulk water is interpreted in terms of the molecular orientation and the local changes in the H-bond network of the cluster. Our results show that, in spite of the presence of a surface moiety of "acceptor-only" molecules, the H-bond network is significantly more labile at the surface than in the bulk part of cluster, and single donor-acceptor arrangements are largely dominant at the interface. Further, although surface water molecules depict in average a single H atom protruding into the vapor, molecules exhibit significant orientational freedom. These results explain the apparently opposite experimental observations from infrared sum frequency generation and X-ray spectroscopy of the liquid-vapor interface. The dipole moment, intramolecular geometry and surface relaxation are also analyzed at light of the different H-bond regions in the cluster.
authors.affiliation: Grupo de Fisica-Matematica da Universidade de Lisboa, Av. Prof. Gama Pinto 2, 1649-003 Lisboa, Portugal.
authors.forename: N
authors.initials: N
authors.lastname: Galamba
authors.forename: B J Costa
authors.initials: BJ
authors.lastname: Cabral
mesh_terms: D006859:Hydrogen / Q000737:chemistry; D006860:Hydrogen Bonding; D008958:Models, Molecular; D010100:Oxygen / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D014867:Water; D006859:Hydrogen; D010100:Oxygen