Polarizabilities of defect-bearing polyenic chains

We investigate the effect of the presence of conformational defects on the polarization response of conjugated chains. Our ab initio results for the polarizabilities of small C2n+1H2n+3+ and C2nH2n+2++ oligomers of polyacetylene confirm previous suggestions that the nonlinear optical properties of these systems are highly dependent on the type of conformational defect introduced. Especially, we call attention to the fact that the first hyperpolarizability of soliton bearing chains has opposite signs for positive and negative defects.