Ab initio study of L-orientational defect in the hydrogen-bonded pattern of liquid water

Current status of the theory of orientational defects in H-bonded pattern of liquid water is briefly reviewed. Ab initio calculated water clusters from dimer to heptamer are thoroughly analyzed in terms of H-bonded pattern. New water heptamer structure of norbornane type is found via ab initio HF 6-311G** calculation. Its normal vibrations are properly assigned. Two ab initio water hexamers that refer to orientational defects are revealed. This is the first evidence of ab initio orientational defect in H-bonded patterns of water clusters. Some properties including normal vibrations of these defects, are studied.