title: Powder diffraction crystal structure analysis using derivative difference minimization: example of the potassium salt of 1-(tetrazol-5-yl)-2-nitroguanidine.
abstract: The crystal structure of the potassium salt of 1-(tetrazol-5-yl)-2-nitroguanidine [K(C2H3N8O2)] was solved and refined from X-ray powder diffraction data by applying the derivative difference minimization (DDM) method. The compound is of interest as an energetic substance. The structure model was found from a Patterson search. The reflection intensities for the Patterson synthesis were derived from the powder profile by applying a newly developed DDM-based profile decomposition procedure. The use of the DDM method allowed successful location and unconstrained refinement of all the atomic positions, including those of three independent H atoms. The advantages of DDM in terms of the precision and reproducibility of the structural parameters are discussed in comparison to Rietveld refinement results. The failure to refine the H-atom positions by the Rietveld method was attributed to systematic errors associated with the background modelling, which are avoided by DDM.
authors.affiliation: Institute of Chemistry and Chemical Technology, 660049 Krasnoyarsk, Russia. leosol@icct.ru
authors.forename: Leonid A
authors.initials: LA
authors.lastname: Solovyov
authors.forename: A M
authors.initials: AM
authors.lastname: Astachov
authors.forename: M S
authors.initials: MS
authors.lastname: Molokeev
authors.forename: A D
authors.initials: AD
authors.lastname: Vasiliev