Static electric properties of conjugated cyclic ketones and thioketones

The results of ab initio calculations of static electric properties of a se ries of cyclic conjugated ketones and thioketones are presented. Dipole mom ents, dipole polarizabilities, as well as the first and second hyperpolariz abilities, were evaluated at different levels of theory: SCF, CASSCF, MP2, CCSD, CCSD(T), and CASPT2 methods were used. Both MP2 and CASPT2 methods ha ve been shown to perform well in the calculation of such properties. The de pendence of the electric properties on the extent of the pi-electron conjug ation and on the replacement of the keto by the thioketo group is analyzed. Cyclic conjugated thioketones are shown to exhibit significant nonlinear e lectric properties which make them prospective building blocks for nonlinea r optical materials. (C) 2000 American Institute of Physics. [S0021- 9606(0 0)31137-0].