Acta Crystallographica Section A Foundations of Crystallography · 1990 · 16.3K citations · 0 references
Natural SciencesMaterials ScienceComputational ChemistryComputational Materials ScienceCrystal StructureAb Initio MethodsCrystal SystemsCrystallographyStructure DeterminationX-ray CrystallographyX-ray DiffractionCrystal Structure AnalysisCrystal Structure DeterminationCrystal Structure RefinementPhase DeterminationSimulated AnnealingSimulated Annealing OptimizationX-ray Crystallographic Refinement
A number of extensions to the multisolution approach to the crystallographic phase problem are discussed in which the negative quartet relations play an important role. A phase annealing method, related to the simulated annealing approach in other optimization problems, is proposed and it is shown that it can result in an improvement of up to an order of magnitude in the chances of solving large structures at atomic resolution. The ideas presented here are incorporated in the program system SHELX-90; the philosophical and mathematical background to the direct-methods part (SHELXS) of this system is described.