Changes in the electronic structure and vibrational potential of hydrogen fluoride upon dimerization: A well-correlated (HF)2 potential energy surface

A large basis, coupled-cluster level treatment of the electronic structure of the hydrogen fluoride dimer has been used to develop an accurate potential energy surface and dipole moment surface. The vibrational motion of the HF subunits was analyzed using a number of different methods for comparison with recent experimental results. Molecular properties averaged over the vibrational motion were also calculated. The vibrational transition frequencies for the two HF stretches in the dimer agree with experiment to 1%, while the shifts in these frequencies agree with experiment to 10 cm−1. The importance of higher order correlation effects and treatment of vibrational anharmonicities is made clear by these results. Transition moments were calculated and show enhancements for both HF stretches in the dimer.