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Inspired by the blind tests of (molecular) organic crystal structure prediction [1], we have decided to perform a blind test for non-molecular inorganic crystal structures. Since in organic structure prediction one deals with the packing of entire (and often rigid) molecules, many constraints are present and the actual number of degrees of freedom is often relatively small. Thus, the search space is not very large and the main challenge is to correctly rank the structures by energy. This requires accurate forcefields that incorporate diverse interactions (Coulomb, van der Waals, hydrogen-bridge, etc.); developing sufficiently accurate forcefields turns out to be a major, if not the main problem in the field of organic crystal structure prediction. For inorganic non-molecular crystals, the number of degrees of freedom is 3N+ 3 (where N is the number of atoms in the unit cell)–and this very often is a large number, reaching 100–300 for …