Electron correlation effects on the electric properties of fluorinated polyacetylene

Using the Hartree-Fock (HF) and second-order Mo̸ller-Plesset perturbation theory (MP2) methods with the 6-31G(d) basis set, we have investigated the chain length dependence of the longitudinal dipole moment and longitudinal components of the static linear polarizability, first and second hyperpolarizabilities of fluorinated polyacetylene chains. It is found that geometry changes caused by the electron correlation (EC) effects imply in marked increases of the electric properties but to obtain a reliable description it is necessary to properly account for both geometric and electronic changes. Based on the fast convergence pattern presented by the MP2∕HF ratios and from the converged HF oligomeric results, we have estimated the MP2 electric properties of long chains. The asymptotic value for the MP2 second hyperpolarizability per unit cell is estimated in 1.9 × 10(8) a.u. This result is one order of magnitude larger than the corresponding result reported for the unsubstituted polyacetylene chains.