title: MAD techniques applied to powder data: finding the structure given the substructure.
abstract: The joint probability distribution function method is applied to multiple-wavelength anomalous dispersion (MAD) powder data. The distributions are calculated by assuming prior knowledge of the scattering intensities at two wavelengths and of the anomalous-scatterer substructure. The method leads to formulas estimating the full structure phases and their reliability. The procedure has been applied to two structures, one unknown and one known; the second was used as a control for the phasing procedure. In spite of the unavoidable peak overlapping in the diffraction pattern, the formulas proved to be very effective. Combined with a new algorithm for phase extension, they enabled the solution of both crystal structures.
authors.affiliation: Istituto di Cristallografia, Sede di Bari, Via G. Amendola 122/o, 70126 Bari, Italy.
authors.forename: Angela
authors.initials: A
authors.lastname: Altomare
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Burla
authors.forename: Corrado
authors.initials: C
authors.lastname: Cuocci
authors.forename: Carmelo
authors.initials: C
authors.lastname: Giacovazzo
authors.forename: Fabia
authors.initials: F
authors.lastname: Gozzo
authors.forename: Anna
authors.initials: A
authors.lastname: Moliterni
authors.forename: Giampiero
authors.initials: G
authors.lastname: Polidori
authors.forename: Rosanna
authors.initials: R
authors.lastname: Rizzi
mesh_terms: D018360:Crystallography, X-Ray / Q000379:methods*; D008962:Models, Theoretical; D015394:Molecular Structure; D011208:Powders / Q000737:chemistry*
chemical_list: D011208:Powders