Structure solution of zeolites from powder diffraction data

2004 ◽  
Vol 219 (12) ◽  
Author(s):  
Allen W. Burton
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Structure Elucidation ◽  
Model Building ◽  
Direct Methods ◽  
Powder Diffraction Data ◽  
Zeolite Structure ◽  
Structure Solution

AbstractThis article reviews methods in structure determination of zeolites from powder diffraction data. First, examples of different model building techniques are discussed. Then the applications and limitations of conventional direct methods in zeolite structure solution are examined. Methods for partitioning overlapping peak intensities are also discussed, and examples are given to illustrate improvements in structure elucidation when these techniques are applied.

FIDDLE. Simultaneous Indexing and Structure Solution from Powder Diffraction Data using a Genetic Algorithm and Correlation Functions

2019 ◽  
Author(s):  
Carmen Guguta ◽  
Jan M.M. Smits ◽  
Rene de Gelder
Keyword(s):  
Genetic Algorithm ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Correlation Functions ◽  
Cross Correlation ◽  
Simultaneous Optimization ◽  
Powder Diffraction Data ◽  
Structure Solution ◽  
Matching Technique

A method for the determination of crystal structures from powder diffraction data is presented that circumvents the difficulties associated with separate indexing. For the simultaneous optimization of the parameters that describe a crystal structure a genetic algorithm is used together with a pattern matching technique based on auto and cross correlation functions.<br>

Challenging structure determination from powder diffraction data: two pharmaceutical salts and one cocrystal with Z′ = 2

2019 ◽  
Vol 234 (4) ◽  
pp. 257-268 ◽  
Author(s):  
Carina Schlesinger ◽  
Michael Bolte ◽  
Martin U. Schmidt
Keyword(s):  
Single Crystal ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Real Space ◽  
Powder Diffraction Data ◽  
The Real ◽  
Pharmaceutical Salts ◽  
Structure Solution ◽  
Space Method

Abstract Structure solution of molecular crystals from powder diffraction data by real-space methods becomes challenging when the total number of degrees of freedom (DoF) for molecular position, orientation and intramolecular torsions exceeds a value of 20. Here we describe the structure determination from powder diffraction data of three pharmaceutical salts or cocrystals, each with four molecules per asymmetric unit on general position: Lamivudine camphorsulfonate (1, P 21, Z=4, Z′=2; 31 DoF), Theophylline benzamide (2, P 41, Z=8, Z′=2; 23 DoF) and Aminoglutethimide camphorsulfonate hemihydrate [3, P 21, Z=4, Z′=2; 31 DoF (if the H2O molecule is ignored)]. In the salts 1 and 3 the cations and anions have two intramolecular DoF each. The molecules in the cocrystal 2 are rigid. The structures of 1 and 2 could be solved without major problems by DASH using simulated annealing. For compound 3, indexing, space group determination and Pawley fit proceeded without problems, but the structure could not be solved by the real-space method, despite extensive trials. By chance, a single crystal of 3 was obtained and the structure was determined by single-crystal X-ray diffraction. A post-analysis revealed that the failure of the real-space method could neither be explained by common sources of error such as incorrect indexing, wrong space group, phase impurities, preferred orientation, spottiness or wrong assumptions on the molecular geometry or other user errors, nor by the real-space method itself. Finally, is turned out that the structure solution failed because of problems in the extraction of the integrated reflection intensities in the Pawley fit. With suitable extracted reflection intensities the structure of 3 could be determined in a routine way.

The ab initio structure determination of [(CH3)4N]2Ge4MnS10 from X-ray powder diffraction data

1995 ◽  
Vol 219 (1-2) ◽  
pp. 111-115 ◽  
Author(s):  
O. Achak ◽  
J.Y. Pivan ◽  
M. Maunaye ◽  
M. Louër ◽  
D. Louër
Keyword(s):  
Ab Initio ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Powder Diffraction Data ◽  
X Ray ◽  
Ab Initio Structure

Structure Determination of CaH2P2O7 From In Situ Powder Diffraction Data

2000 ◽  
Vol 321-324 ◽  
pp. 374-379 ◽  
Author(s):  
J. Trommer ◽  
M. Schneider ◽  
H. Worzala ◽  
Andrew N. Fitch
Keyword(s):  
Powder Diffraction ◽  
Diffraction Data ◽  
Structure Determination ◽  
Powder Diffraction Data
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