Vibrationally averaged magnetizabilities and rotational g tensors of the water molecule

Using large basis sets, London atomic orbitals and large multiconfigurational self-consistent field wavefunctions, we have calculated the molecular magnetizability and rotational g tensors of the water molecule, including zero-point vibrational corrections. Whereas the vibrational corrections are found to be negligible for the magnetizability, the inclusion of vibrational effects (being of the order of 2%) makes our calculated rotational g tensor agree well with experimental observations for D2O. For H2O we show that earlier agreement between theory and experiment is fortuitous and arises from the neglect of zero-point vibrational contributions in both approaches. We suggest that the rotational g tensor of H2O and HDO be remeasured.