The Rotational g Tensor as a Benchmark for Ab InitioMolecular Property Calculations

Ab initio calculations using large multiconfigurational self-consistent field wave functions and density functional theory are presented for the rotational g tensors of HOF, H2O, H2S and O3. Rapid convergence toward the basis-set limit is ensured using rotational London atomic orbitals. The effect of zero-point vibrational corrections and the choice of molecular geometries are analyzed and the results are compared to highly accurate experimental results obtained by microwave Zeeman spectroscopy and by various molecular beam techniques. Electron-correlation corrections and zero-point vibrational corrections are found to be equally important and both must be taken into account when comparing with highly accurate experimental data.