Density functional and electron correlated study of five linear birefringences - Kerr, Cotton-Mouton, Buckingham, Jones and Magneto-electric - in gaseous benzene

We present the results of an extended study of five birefringences—Kerr, Cotton–Mouton, Buckingham, Jones, and Magnetoelectric—on benzene in the gas phase. The relevant molecular quantities—first-order properties, linear, quadratic, and cubic response functions—are computed employing the density-functional theory (DFT) response theory, with a choice of functionals. In some cases, different functionals are employed for the wave-function computational step and for the subsequent analytical response calculation to determine the combination yielding at the same time the optimal energy and energy derivative results. Augmented correlation consistent basis sets of double and triple zeta quality are used. The DFT results are compared to those obtained at the Hartree–Fock level and in some cases within a coupled cluster singles and doubles electronic structure model. The study tries to assess the ability of the DFT response theory to describe a wide range of properties in a system of rather large size and high complexity. The relative strength of the five birefringences for plausible experimental conditions is determined and, when possible, comparison is made with the results of the measurements.