AB-INITIO THEORETICAL-STUDY OF SURFACE AND INTERIOR STRUCTURES OF THE NA(H2O)4 CLUSTER AND ITS CATION

The structures and stabilities of Na(H2O)4 and its cation have been investigated at the ab initio HF/6-31 + G(d), HF/6-31++G(d, p) and MP2/6-31+G(d) levels. For the neutral complex, both the 'surface' structure and the 'interior' structure are found to be minima on the potential energy surface. The energies of these two structures are close to each other at the highest level. For both surface and interior structures, some characteristic features are found in the vibrational spectra, which may be the best method for experimental identification. For the cation cluster, only the 'interior' structure is stable.