Theoretical determination of the vibrational and electronic (hyper)polarizabilities of C4H4X (X=O, S, Se, Te) heterocycles

摘要: Electronic, pure vibrational and dispersion contributions to the linear polarizability, α, first hyperpolarizability, β, of group 16 chalcogenides C4H4X (X=O, S, Se, Te) have been studied by ab initio calculations using 6-31G*, Sadlej POL, correlation consistent Dunning aug-CEP-31G basis sets. Electron was introduced through MP2 theory. Vibrational (hyper)polarizabilities, evaluated within double harmonic oscillator approximation, were analyzed in terms single normal mode contributions. They found be a fraction electronic counterpart. βv does not show clear dependence on heavy atom, contrary βe, which steadily increases along series. The βv/βe ratio is very dependent on set, decreasing also changing sign presence diffuse functions. Frequency-dependent (hyper)polarizabilities 0.02–0.16 a.u. frequency range. In low-frequency range they can fitted into power series expansion ω. accord with theory, second-order coefficients β are same for both SHG EOPE non-linear optical processes, while the α be related lowest excitation energy.