title: Subtleties in crystal structure solution from powder diffraction data using simulated annealing: ranitidine hydrochloride.
abstract: Recent advances in crystallographic computing and availability of high-resolution diffraction data have made it relatively easy to solve crystal structures from powders that would have traditionally required single crystal samples. The success of direct space methods depends heavily on starting with an accurate molecular model. In this paper we address the applicability of using these methods in finding subtleties such as disorder in the molecular conformation that might not be known a priori. We use ranitidine HCl as our test sample as it is known to have a conformational disorder from single crystal structural work. We redetermine the structure from powder data using simulated annealing and show that the conformational disorder is clearly revealed by this method.
authors.affiliation: Department of Physics and Astronomy, State University of New York at Stony Brook, Stony Brook, New York 11794-3800, USA.
authors.forename: Ashfia
authors.initials: A
authors.lastname: Huq
authors.forename: P W
authors.initials: PW
authors.lastname: Stephens
mesh_terms: D000465:Algorithms; D018360:Crystallography, X-Ray; D006635:Histamine H2 Antagonists / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D033362:Powder Diffraction; D011899:Ranitidine / Q000737:chemistry*
chemical_list: D006635:Histamine H2 Antagonists; D011899:Ranitidine