Ab initio quantum chemistry and semi-empirical description of solid state phases under high pressure: Chemical applications

There is nowadays a consensus that the structures of crystals at high pressure provide useful chemical information, at least in three important fields: (a) discoveries of new polymorphs and mechanisms of solid-solid transitions or high-pressure crystallizations; (b) intra- and inter-molecular bonding as a function of the external stress; (c) structure-property correlation. While experimental evidence is vital at high pressure, there is an increasing need of support from theoretical work, in particular for predicting new phases and their structure, for explaining the mechanisms of phase transformations and for computing and predicting the material properties. In this chapter, a brief survey of quantum mechanical descriptions of the solid state is given, summarizing the state of the art in the field and the potential developments. Some examples will illustrate the successful synergy between theory and experiment in studies on molecular crystals at high pressure. © 2010 Springer Science+Business Media B.V.