Ab initio and density functional theory calculations of the dipole polarizability and the second dipole hyperpolarizability of benzene

Abstract

AbstractThe linear dipole polarizability α and nonlinear second dipole hyperpolarizability γ of benzene were calculated using the ab initio SCF–MO restricted Hartree–Fock (HF) method. The coupled perturbed HF and time‐dependent HF (TDHF) methods were used for the evaluation of the static and dynamic properties, respectively. The TDHF approach was applied at different optical frequencies, and the second hyperpolarizability γ was evaluated for different optical processes. Electron correlation was taken into account by using the Møller–Plesset perturbation theory (MP2) and the density functional theory B3LYP hybrid approach, with a finite field method, with electric fields of ±0.01, ±0.02, ±0.03, and ±0.04 a.u. used. Benzene was assumed to have a D6h geometry, and the standard STO/6‐31+G(d,p) (A) and optimized STO/6‐31+G(d*,p) (B) basis sets were employed for the calculations. In the optimized basis set, the d exponent of the C atomic function was varied in order to obtain a maximum static benzene γ at the TDHF level of theory. This optimized basis set was able to gives values for the (hyper)polarizabilities of benzene that agree excellently with experimental results and previous calculations. The calculated properties were analyzed in terms of the Laplacian of the electron density calculated using the atoms in molecules method due to Bader. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002