Theoretical Studies of Large (H₂O)_32-35 Clusters

Water clusters, (H₂O)_32-35, were studied by applying the intermediate neglect of differential overlap selfconsistent field restricted Hartree-Fock method (INDO SCF RHF) after parametrization for H and O atoms. The 32-mer single-cage clusters with no water molecule within the cavity have stabilization energy (SE)/ monomer values ranging from 9.72 to 11.15 kcal/mol and the 33- and 34-mer structures with 1 and 2 water molecules within the 32-mer cage cavity have SE/monomer values of 10.59-10.78 and 10.88-11.23 kcal/ mol, respectively. The 35-mer isomers with water molecules bonded within and outside of the 32-mer cage cavity are significantly less stable (SE/monomer values 10.24-10.87 kcal/mol) than the fused cage isomers (SE/monomer 11.23- 11.41 kcal/mol) in which two dodecahedral cages of O atoms share a pentagonal face. On the basis of this study and others reported earlier, we can suggest that as the cluster size increases the multiple cage formation becomes favorable.