title: Concerted hydrogen-bond breaking by quantum tunneling in the water hexamer prism.
abstract: The nature of the intermolecular forces between water molecules is the same in small hydrogen-bonded clusters as in the bulk. The rotational spectra of the clusters therefore give insight into the intermolecular forces present in liquid water and ice. The water hexamer is the smallest water cluster to support low-energy structures with branched three-dimensional hydrogen-bond networks, rather than cyclic two-dimensional topologies. Here we report measurements of splitting patterns in rotational transitions of the water hexamer prism, and we used quantum simulations to show that they result from geared and antigeared rotations of a pair of water molecules. Unlike previously reported tunneling motions in water clusters, the geared motion involves the concerted breaking of two hydrogen bonds. Similar types of motion may be feasible in interfacial and confined water.
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK. Department of Chemistry, Durham University, South Road Durham DH1 3LE, UK.
authors.forename: Jeremy O
authors.initials: JO
authors.lastname: Richardson
authors.affiliation: Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, VA 22903, USA.
authors.forename: Cristóbal
authors.initials: C
authors.lastname: Pérez
authors.affiliation: Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, VA 22903, USA.
authors.forename: Simon
authors.initials: S
authors.lastname: Lobsiger
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
authors.forename: Adam A
authors.initials: AA
authors.lastname: Reid
authors.affiliation: Dean's Office, College of Arts and Sciences, and Department of Chemistry, Bucknell University, Lewisburg, PA 17837, USA.
authors.forename: Berhane
authors.initials: B
authors.lastname: Temelso
authors.affiliation: Dean's Office, College of Arts and Sciences, and Department of Chemistry, Bucknell University, Lewisburg, PA 17837, USA.
authors.forename: George C
authors.initials: GC
authors.lastname: Shields
authors.affiliation: Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warszawa, Poland.
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Kisiel
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Wales
authors.affiliation: Department of Chemistry, University of Virginia, McCormick Road, Charlottesville, VA 22903, USA.
authors.forename: Brooks H
authors.initials: BH
authors.lastname: Pate
authors.affiliation: Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK.
authors.forename: Stuart C
authors.initials: SC
authors.lastname: Althorpe