Clusters and Small Homologous Series

6 Clusters and Small Homologous Series. - Raptis et a/.150 report studies on the polysulfanes, H2S , using MNDO and ab initio methods. The static and dynamic polarizabilities and hyperpolarizabilities are calculated and the authors find that the forms of change exhibited by a and are similar, so that the variation of the former may be used to predict that of the latter. Large changes in the hyperpolarizability with molecular structure are observed. 

Reiss and Papadopoulos151 have used a range of ab initio methods, from restricted Hartree-Fock and unrestricted Hartree-Fock (UHF) to calculate the static polarizability and second hyperpolarizability of B4 clusters. UHF gives more reliable geometries at the expense of spin contamination and it is found that there is considerable oscillatory behaviour as the level of MBPT is increased ( , n = 2, 3,4). 

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