Journal of Chemical Physics, Vol.100, No.11, 7995-8002, 1994
Vibrational Circular-Dichroism Intensities by Ab-Initio 2nd-Order Moller-Plesset Vibronic Coupling Theory
The vibronic coupling theory (VCT) of Nafie and Freedman for evaluating vibrational circular dichroism (VCD) intensities has been implemented at the level of ab initio second-order Moller-Plesset perturbation theory (MP2). This method, in conjunction with the MP2 force field, is applied to calculate VCD spectra of (S,S)-2,3-dideuteriooxirane and (S)-NHDT. Several basis sets, namely 6-31G Alpha(*), 6-31G(*(03)), vd/3p, and vd/3p(u) are used in the calculations. Comparisons with. the experimental results for oxirane and alternate high level calculations in the case of NHDT show that VCT/MP2 with a near-Hartree-Fock limit basis set will predict nearly quantitatively values of vibrational rotatory strengths. The inclusion of electron correlation at the MP2 level into calculation of the atomic axial tensors is important for obtaining reliable vibrational properties for the conventional 6-31G(*) basis set. The 6-31G(*(0.3)) basis set, which has previously proved to be highly successful in predicting VCD spectra with the VCT-SCF method, yields only modest improvement at the MP2 level.