Direct ab initio variational calculation of vibrational energies of the H₂O⋯Cl^- complex and resolution of experimental differences

We report the direct ab initio calculation of vibrational energies of the chloride anion - water complex by interfacing the code MULTIMODE, which does variational calculations of vibrational energies, with GAUSSIAN, which does ab initio calculations of electronic energies. Convergence of the results with respect to the level of mode-coupling considered indicates that the present results are reliable enough to distinguish between two sets of conflicting experimental reports of these vibrational energies.