Coupled-Hartree-Fock calculations of the third-order hyperpolarizabilities of substituted polydiacetylenes

Abstract

Coupled-Hartree-Fock calculations of the static third-order hyperpolarizabilities (γ) in the chain direction for regular polydiacetylene and several donor (D)-acceptor (A) substituted polydiacetylene oligomers through C42H24 are carried out at the level of the INDO approximation. The modes of the variations in γ with the increasing chain length are investigated for the different types of polydiacetylene systems. The γ density analysis is carried out to elucidate the spatial characteristics of γ. Results for sufficiently long oligomers are extrapolated to an infinity of the chain length to predict the intrinsic γ values per repeating unit of the polydiacetylenic chains. © 1991.