Ab initio calculation of atomic axial tensors and vibrational rotational strengths using density functional theory

We document a new density functional theory (DFT) methodology for the ab initio calculation of atomic axial tensors (AATs) using direct, analytical derivative methods and gauge-invariant atomic orbital (GIAO) basis sets. AATs are calculated for ethylene oxide. Their accuracy is assessed using AAT sum rules and the experimental electric dipole moment and paramagnetic susceptibility tensor. AATs calculated for the chiral molecule 6,8-dioxabicyclo[3.2.1]octane, in combination with DFT harmonic force fields and atomic polar tensors, are used to predict vibrational rotational strengths and vibrational circular dichroism (VCD) spectra. Their accuracy is assessed by comparison with the experimental rotational strengths and VCD spectrum.The dependence of calculated results on density functional and basis set is explored. The DFT calculations are compared to SCF (Hartree-Fock) calculations carried out in parallel.