Which organic crystal structures are predictable by lattice energy minimisation?
A survey of the molecules which have been used in crystal structure prediction studies is presented. The results of these studies have been analysed in terms of whether the experimentally observed crystal structures are found at or near the global minimum in the lattice energy. The results suggest that whilst some crystal structures can be predicted just on the basis of lattice energy searches, there is yet insufficient experience to judge for which molecules this energetic criterion is sufficient, within the limitations of current force-field accuracy. The molecules chosen to test crystal structure prediction methods appear to be biased away from the types that would be expected to be readily predictable and suitable for crystal engineering. The survey highlights the need for more theoretical and experimental collaboration to understand what determines whether a molecule's crystal structure will be so favourable that other polymorphs are unlikely.