SIMULATED ANNEALING FOR PHASING USING SPATIAL CONSTRAINTS

Phase refinement using partial structural information is an important step in the treatment of crystallographic data. An optimization proced ure is presented that, in contrast to conventional Fourier methods, ta kes into account the spatial dependence of the accuracy of the partial information for electron density. Annealing studies for a test case s how that this optimization procedure is tractable for system sizes rel evant to the treatment of protein diffraction data and requires substa ntially less structural information for accurate phase refinement than Fourier methods.