Analysis of some significant processes for molecular polarization

Abstract

The polarisability, the first and second hyperpolarisabilities of NH₂—C₆H₄—C_nH_n—CHC₅H₄, where n= 2, 4 and 6, as well as of some related compounds are reported. The effects of isomerism, conjugation and charge-transfer on the properties are discussed. In addition the influence of increasing the length of the conjugation path on the linear and non-linear electric properties has been commented upon. The properties have been computed using an extended-basis CNDO wavefunction and the coupled Hartree–Fock perturbation theory of McWeeney et al. The employed basis sets have been shown to give polarisability (α) and second hyperpolarisability (γ) values, for some fragments of the considered molecules, in reasonable agreement with the experimental results.