Charge flipping for routine structure solution

Abstract

Charge flipping can be routinely used for solving small-molecule structures measured at atomic resolution. It is shown by benchmark tests that its performance is at least equal to that of direct methods in terms of the speed of solution and the quality of the resulting structure. There are, however, cases where charge flipping may be more suitable than direct methods for solving structures,viz.where space-group symmetry is uncertain from the analysis of systematic extinct reflections. The latest charge-flipping enhancements, such as the minimum superposition map procedure and the AAR algorithm, are also tested against database structures and compared with the usual variant. Default parameters are determined which yield a maximum of solved structures.