title: Phase determination via Sayre-type equations with anomalous-scattering data.
abstract: The necessary background for the analysis of complex-valued electron-density maps is established. Various systems of structure-factor equations of convolutional type akin to Sayre's squaring method equations are tested for agreement on the real and imaginary parts of the electron density as well as approximations thereof. A system of convolutional structure-factor equations holding in a complex-valued electron density generated by two atom types is developed. The scope of application of these equations is determined and it is shown that the equations provide a method of extrapolating high-resolution phases from a low-resolution base phase set without introducing further model bias. Additional applications to phase refinement are explored.
authors.affiliation: Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill, North Carolina, USA.
authors.forename: J
authors.initials: J
authors.lastname: Roach
authors.forename: P
authors.initials: P
authors.lastname: Retailleau
authors.forename: C W
authors.initials: CW
authors.lastname: Carter
mesh_terms: D018360:Crystallography, X-Ray; D005583:Fourier Analysis; D008958:Models, Molecular; D008962:Models, Theoretical; D009113:Muramidase / Q000737:chemistry*
chemical_list: D009113:Muramidase