Hartree-Fock and density functional theory ab initio calculation of optical rotation using GIAOs: Basis set dependence

Ab initio Hartree-Fock (HF) and density functional theory (DFT) calculation s of the electric dipole-magnetic dipole polarizability beta(alpha beta) ar e reported for the chiral molecules methyloxirane (1) and trans-dimethylthi irane (2) in the static limit. Values of beta = 1/3Tr[beta(alpha beta)] obt ained thence are used to predict the specific optical rotations [alpha](D) of 1 and 2. Gauge-including atomic orbitals (GIAOs) are used to ensure orig in independence of beta and [alpha](D). beta and [alpha](D) values converge slowly to the complete basis set limit. Basis sets including diffuse funct ions are required to achieve reliable results. HF and DFT values of beta(al pha beta) differ generally by 10-30%. Calculated [alpha](D) values for 1 an d 2 obtained using large basis sets agree well with experimental values in sign and magnitude. The deviations can be attributed in part to the neglect of the frequency dependence of beta and of solvent effects.