Push-pull chromophores incorporated in 1,3-dithiol-2-ylidene moiety as newelectrooptics materials

Experimental and theoretical investigations of influence of the push-pull c hromophores incorporated in the 1.3-dithiol-2-ylidene moiety as the electro n donating part on linear electrooptic (Pockels) coefficient have been perf ormed. The proposed theoretical approach is based on geometry optimization of the molecule and appropriate quantum chemical calculations. Intermolecul ar interactions are evaluated within a framework of long-range intermolecul ar interactions. Based on approach combining local density approximation (L DA) and Hartree-Fock method we have revealed good correlation between the e xperimental and theoretical values of linear electrooptical coefficients (E OC). Contribution of electronic UV and phonon modes to EOC tensor component r(111) (lambda = 633 mn) was evaluated. The phonon and UV modes have been found to be very sensible to substitution of the chromophores. Analysis of contributions of particular molecular group is done. (C) 2001 Elsevier Scie nce B.V. All rights reserved.