ELECTRONIC-STRUCTURE AND NONLINEAR OPTICAL-PROPERTIES OF PUSH-PULL CONJUGATED MOLECULES

We present a review of ab initio calculations we recently performed on organic molecules presenting promising quadratic nonlinear optical properties. These molecules constitute so-called push-pull conjugated compounds in which a conjugated segment is capped at one end by an acceptor group and at the other end by a donor group. We focus on three series of systems: (i) p-amino-p'-nitrodiphenylacetylenes for which "unusual" distorsion patterns have been recently reported; (ii) benzodithiapolyenals, which present among the largest second-order polarizabilities ever measured; and (iii) 2-methylene-2H-pyrrole derivatives. Our results are found to provide a detailed understanding of the available experimental data.