Polymorph Prediction of Small Organic Molecules, Co-crystals and Salts
Crystal structure prediction is regarded by some as the holy grail of crystal engineering because reliable and accurate prediction of the polymorphs that a compound can crystallise in would allow the design of organic materials with specific properties from first principles. This contribution provides an overview of the current status of crystal structure prediction of small organic molecules in general and focuses on the specific issues encountered in the prediction of co-crystal and salt structures. Both the global optimisation problem of searching for all possible crystal structures of a compound and the problem of calculating accurate lattice energies in order to rank potential crystal structures according to stability are discussed. A number of illustrative examples are presented, including an overview of the Cambridge Crystallographic Data Centre's blind tests in crystal structure prediction, as well as some examples of co-crystals, solvates and salts.