Dimecres, 23 de maig de 2007, a les 12h.
Sala de Juntes de la Facultat de Geologia
Per Kenneth D.M. Harris, School of Chemistry, Cardiff University, Park Place, Cardiff CF10 3AT, Wales

Many solids can be prepared only as microcrystalline powders and are therefore not suitable for structural charecterization by conventional single-crystal X-ray diffraction techniques. For such materials, it es necessary to tackle structure determination using powder X-ray diffraction data. Although traditional tecniques for structure solution from poeder X-ray diffraction data have been applied successfully un many cases, organic molecular crystal represent a particulary challenging case. For These reasons, we are focusing on the development, implementation and optimization of new strategies for structure solution from powdwr- X-ray diffraction data, with particular emphasis on tackling the specific challenges encountered for molecular crystals.. Our techiques are based on the direct-spece strategy, in which a hypersurface defined by the powdwe profile R-factor (Rwp) is searched using Monte Carlo or Genetic Algoritm techniques, with particular focus in recent years on The lecture will give an overview of current opportunities for structure determination of molecular crystals from powder X-ray diffraction data. Recent results from the application of our techniques to determine crystal structures of molecular materilas will be presented, encompassing examples from powdwe X-ray diffraction data. Recent results from thr application of our techniques to determine crystal structures of molecular materilas will be presented, encompassing examples from several different fields of science.