Potential curves for proton motion in H-bonded systems: HF and H2O polymers

The presence of long range coupling between hydrogen atoms is shown for the HF and H₂O hydrogen bonded systems. The coupling of H atoms critically depends on the spatial orientation of the H atoms being considered. Explicit calculations of the potential curves of the protons are performed using as a model a ring of six HF, or H₂O, molecules. The method of calculation is the CNDO/2. The strong similarities of the results for H₂O and HF polymers supports the conclusion that the coupling is essentially due to factors such as the asymmetric equilibrium position of the H atoms, the high electronic polarizability of the system, etc.