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 procedure is presented that, in contrast to conventional Fourier methods, takes into account the spatial dependence of the accuracy of the partial information for electron density. Annealing studies for a test case show that this optimization procedure is tractable for system sizes relevant to the treatment of protein diffraction data and requires substantially less structural information for accurate phase refinement than Fourier methods.