부산대학교 도서관

The contribution of the π electrons to the polarizabilities of finite and infinite systems have been calculated for infinite one-dimensional chains modeling organic polymers, such as polyacetylene and various polyheterocycles. In the first part, results obtained previously using a finite-field technique within the Hückel and Pariser–Parr–Pople (PPP) models applied to polymers containing up to 400 atoms have been compared to results obtained from the sum-over-states (SOS) perturbation theory. The calculated polarizabilities depend on the type of monomer following polyacetylene ≥ polythiophene ≥ polypyrrole. This result is qualitatively independent on the type of model or formalism. In the second part, we present results of the application of the Genkin–Mednis formalism within the PPP model to the calculation of the π polarizability of infinite one-dimensional chains. Numerical difficulties arise from the phase of the linear-combination-of-atomic-orbital (LCAO) coefficients corresponding to different k points. It is necessary to monitor these phases in order to obtain reliable data. The Genkin–Mednis polarizabilities are in excellent agreement with the asymptotic values obtained using the SOS method on oligomers. [ABSTRACT FROM AUTHOR]