Quantum mechanical study of the structure and stability of molecular van der Waals' clusters I: hydrates of SO2

The structure and stability of the mixed clusters SO₂(H₂O)_n, n ranging from 1 to 4, have been examined using semi-empirical quantum mechanical Hartree Fock methods with the improved PM3 parameter set as implemented in MOPAC [1]. Limited molecular dynamics studies together with investigation of the potential surface reveal potential barriers of 1 kcal/mol or less between many of the stable structures for a cluster of a given size. For n=1,2 the results are compared with those ofab initio calculations using a double zeta basis at the MP4 level.Supported in part by NSF Research Experience for Undergraduates