The electric dipole moment of ArH+. Disagreement between theory and experiment

The experimentally determined dipole moment of the ArH+ molecular ion (1.4 D, 1.59 D) is in considerable disagreement with previous ab initio calculations (2.2 D). In this work we present further theoretical evidence strongly supporting a dipole moment of 2.1±0.1 D. We have carried out an extensive basis set study and calculated the dipole moment using the coupled cluster analytical energy gradient and polarization propagator techniques. Based on a theoretical determination of the equilibrium rotational g factors for ArH+ and ArD+ we conclude that the extrapolation of the experimentally determined g factors to their equilibrium values is the main source of the discrepancy between theory and experiment.