Ab initio and semi-empirical studies of the static polarizability and the second hyperpolarizability of diamond: finite T-d symmetry models from CH4 to C281H172

The mean static polarizability and second hyperpolarizability of a series o f diamond-like molecules capped by hydrogen atoms have been calculated. Bot h semi-empirical (MNDO. AM1, PM3) and ab initio Hartree-Fock (with basis se ts STO-3G, 3-21G, 6-31G**) methods have been used. The results enable the d etermination of the mean polarizability of diamond and on estimation of the second hyperpolarizability:. The values an consistent with the little expe rimental data available. (C) 2000 Elsevier Science B.V. All rights reserved .