Structure and vibrational spectroscopy of the water dimer using quantum simulation

A method is described for calculating the vibrational frequencies of a molecular cluster using a combination of quantum simulation and local-mode variational theory. The method is applied to the water dimer and results are compared with normal-mode theory, frozen field local-mode theory, and with experiment. It is shown that the new approach is more rapidly convergent than the other techniques. Also, providing a suitable potential surface is available, the method is readily applicable to other molecular clusters.