HYPERPOLARIZABILITIES OF ORGANIC-MOLECULES - AB-INITIO TIME-DEPENDENTCOUPLED PERTURBED HARTREE-FOCK-ROOTHAAN STUDIES OF BASIC HETEROCYCLICSTRUCTURES

The linear polarizability, alpha, the first hyperpolarizability, beta, and the second hyperpolarizability, gamma, of three different classes of basic heterocyclic organic structures have been calculated by the ab inio time-dependent coupled Hartree-Fock-Roothaan method using a 4- 31G basis set augmented by diffuse p and d functions. For the alpha an d gamma coefficients, the calculated orders thiophene > pyrrole > fura n for the five-membered rings; pyridine > pyrazole > s-triazine for th e aromatic bases; and benzothiazole, oxazole for the fused ring system s show a qualitative relationship with the corresponding order in Delt a epsilon(HOMO-LUMO) of the respective group of molecules. The beta va lues do not appear to show a discernible trend. The dispersion of alph a(-omega;omega) and those of gamma(-omega;0,0,omega), gamma(-omega;ome ga,omega,-omega), gamma(-2 omega;0,omega,omega), and gamma(-3 omega;om ega,omega,omega) in the case of the five-membered rings are also repor ted.