title: Probing Defects and Correlations in the Hydrogen-Bond Network of ab Initio Water.
abstract: The hydrogen-bond network of water is characterized by the presence of coordination defects relative to the ideal tetrahedral network of ice, whose fluctuations determine the static and time-dependent properties of the liquid. Because of topological constraints, such defects do not come alone but are highly correlated coming in a plethora of different pairs. Here we discuss in detail such correlations in the case of ab initio water models and show that they have interesting similarities to regular and defective solid phases of water. Although defect correlations involve deviations from idealized tetrahedrality, they can still be regarded as weaker hydrogen bonds that retain a high degree of directionality. We also investigate how the structure and population of coordination defects is affected by approximations to the interatomic potential, finding that, in most cases, the qualitative features of the hydrogen-bond network are remarkably robust.
authors.affiliation: Laboratory of Computational Science and Modeling, IMX, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland.
authors.forename: Piero
authors.initials: P
authors.lastname: Gasparotto
authors.affiliation: Condensed Matter Physics Section, The Abdus Salaam International Center for Theoretical Physics , Strada Costiera 11, 34151 Trieste Italy.
authors.forename: Ali A
authors.initials: AA
authors.lastname: Hassanali
authors.affiliation: Laboratory of Computational Science and Modeling, IMX, École Polytechnique Fédérale de Lausanne , 1015 Lausanne, Switzerland.
authors.forename: Michele
authors.initials: M
authors.lastname: Ceriotti