Microscopic Study of Fluoride-Water Clusters

We have carried out ab initio calculations on the structure and energetics of F - (H 2 O) n , n=1-6, clusters at the self-consistent mean-field (SCF) and second-order Moller-Plesset (MP2) levels of theory. The rather strong F - -H 2 O interactions determine the strength of the hydrogen bonds between the water molecules and thus the structure of the clusters. Our data show that a transition from a predominant surface state to an interior state is observed at n=4 and 5. By comparison with our previous calculations of other halide-water clusters, the strength of the halide-water interactions appears to be an important determining factor in the size at which a surface to interior transition is observed