Hydrogen Bond in Solids Under High Pressure

Hydrogen bond represents a directional molecular interaction with the strength between a van der Waals interaction and a covalent bond. Its directional feature makes it an important intermolecular interaction in biological molecules, many organic and inorganic compounds, and hydrous minerals. Alterations of hydrogen bond strength under pressure lead to several significant changes in the spectral and structural features of hydrogen bonded solids. Pressure can also bring about symmeterization of hydrogen bonds. In this chapter, we present the systematics observed in the hydrogen bonded compounds under pressure, including the features of H---H repulsion.