The proton potential in short hydrogen bonds

The state of knowledge of the proton potential in systems for which double minimum and symmetrical, single minimum type curves have been envisaged is critically reviewed. In particular, the proposed model potentials for carboxylic acids, for KDP type ferroelectrics and for the shortest hydrogen bonds are confronted with experimental data, particularly from vibrational spectra. The early attempts at explaining the complex features in the AH stretching region by level splitting in one-dimensional double minimum potentials have not been successful. The interest in the profile of the potential surface is shifted from this aspect to its role in anharmonic interaction based general band-shaping mechanisms.