A hybrid minimal principle for the crystallographic phase problem

Simulated annealing is used to solve the X-ray phase problem formulated as a minimization problem. The cost function consists of two parts, one repres ents the discrepancy between measured and calculated intensities while the other monitors the probability distribution of the triplets. From a random real-space structure at the start, the atoms are moved one by one to gradua lly reduce the cost function until the best structure emerges. Trial calcul ations for structures including hexadecaisoleucinomycin (HEXIL) are present ed. Comparison of this method with other related methods is made.