Pressure variation of the O-H bond length in O-H center dot center dot center dot O hydrogen bonds

Recent neutron diffraction studies have shown that O-H bond lengths do not show the same variation under pressure as given by the well-known empirical relationship between O-H and O-H---O bond distances. In this paper, we describe a modification to include pressure effects in an earlier potential function for isolated hydrogen bonds and examine the inverse co-relation between O-H and O-H---O distances. This modification takes into account the repulsive stresses caused by other atoms which come close to the hydrogen bond on compression. However, this produces only small differences in O-H values from the unmodified ones and therefore the results indicate that there may be systematic errors present in the experimental powder neutron diffraction values of O-H distances measured under pressure.