Dissociation of hydrogen fluoride in HF(H2O)7

We have previously demonstrated that H-bond arrangement has a significant influence on the energetics, structure and chemistry of water clusters [J.-L. Kuo, C. V. Ciobanu, I. Shavitt, L. Ojamae, and S. J. Singer, J. Chem. Phys., 118, 3583 (2003)]. In this work, the effect of H-bond orientation on the dissociation of hydrogen fluoride with seven water molecules is studied by means of graph theory and high level ab initio methods. It is found that cubic structures of HF(H2O)(7) are more stable than structures of other topologies reported in the literature. Electronic calculations on all possible H-bond orientations of cubie-HF(H2O)(7) show that ionized structures are energetically more favorable than nonionized ones. This is an indication that seven water molecules might be capable of ionizing hydrogen fluoride. (C) 2004 American Institute of Physics.