A procedure towards the automatic solution of crystal structures by means of topological analysis of Fourier maps

The last step of a crystal structure determination that requires human intervention is the interpretation of Fourier maps, displayed as peaks in a favourable projection. Crystallographers infer bonding by empirically assigning bonds between peaks via purely geometrical criteria. In this paper, a network connecting peaks and passes of the density function is suggested in order to avoid human intervention and bonding inference. A completely automatic algorithm for the full analysis of critical points and recognition of the molecular graph in Fourier maps has been developed and implemented into the package DIRDIF. This procedure has been applied successfully to a wide variety of crystal structures. In most cases, the complete structure is recovered and the connectivity matrix is constructed without any user intervention.