Ab Initio Calculation of Polarizability and Second Hyperpolarizability in Benzene Including Electron Correlation Treated by Moller-Plesset Theory.

摘要

We present an ab initio calculation of polarizability and second hyper polarizability for the benzene molecule including electron-electron correlation. The finite field method is used. For each selected strength of the applied electric field the energy of the benzene molecule is calculated using the self-consistent field method (SCF) as well as with its Moller-Plesset correction in the second Order (MP-2). Then the microscopic optical nonlinear responses are calculated by fitting both the SCF energy and the MP-2 energy to a polynomial in the field strength. We find that electron correlation significantly enhances the second hyperpolarizability. For the polarizability, our computed value shows an excellent agreement with the experimentally measured value. For the second hyperpolarizability, the computed value using MP-2 energy shows a reasonable agreement with that reported by value using MP-2 energy shows a reasonable agreement with that reported by the electrical field induced second harmonic (EFISH) generation but a poor agreement with the result of degenerate four wave mixing (DFWM). Finally, we also compare our ab initio results with those previously reported using semiempirical methods. Keywords: Optical properties; Electrical properties; Structural properties; Reprints. (kt)