scholarly journals Crystal structure prediction of organic pigments: quinacridone as an example

2007 ◽  
Vol 40 (1) ◽  
pp. 105-114 ◽  
Author(s):  
N. Panina ◽  
F. J. J. Leusen ◽  
F. F. B. J. Janssen ◽  
P. Verwer ◽  
H. Meekes ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Energy Minimization ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
X Ray ◽  
Organic Pigments ◽  
Structural Database ◽  
Diffraction Patterns ◽  
Experimental Structure

The structures of the α, β and γ polymorphs of quinacridone (Pigment Violet 19) were predicted usingPolymorph Predictorsoftware in combination with X-ray powder diffraction patterns of limited quality. After generation and energy minimization of the possible structures, their powder patterns were compared with the experimental ones. On this basis, candidate structures for the polymorphs were chosen from the list of all structures. Rietveld refinement was used to validate the choice of structures. The predicted structure of the γ polymorph is in accordance with the experimental structure published previously. Three possible structures for the β polymorph are proposed on the basis of X-ray powder patterns comparison. It is shown that the α structure in the Cambridge Structural Database is likely to be in error, and a new α structure is proposed. The present work demonstrates a method to obtain crystal structures of industrially important pigments when only a low-quality X-ray powder diffraction pattern is available.

New similarity index for crystal structure determination from X-ray powder diagrams

2005 ◽  
Vol 38 (6) ◽  
pp. 861-866 ◽  
Author(s):  
Detlef Walter Maria Hofmann ◽  
Ludmila Kuleshova
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Structure Prediction ◽  
Similarity Index ◽  
Crystal Structure Determination ◽  
Crystal Structure Prediction ◽  
X Ray ◽  
Organic Pigments ◽  
Structure Solution ◽  
Similarity Indices

A new similarity index for automated comparison of powder diagrams is proposed. In contrast to traditionally used similarity indices, the proposed method is valid in cases of large deviations in the cell constants. The refinement according to this index closes the gap between crystal structure prediction and automated crystal structure determination. The opportunities of the new procedure have been demonstrated by crystal structure solution of un-indexed powder diagrams of some organic pigments (PY111, PR181 and Me-PR170).

scholarly journals ROY revisited, again: the eighth solved structure

2018 ◽  
Vol 211 ◽  
pp. 477-491 ◽  
Author(s):  
Melissa Tan ◽  
Alexander G. Shtukenberg ◽  
Shengcai Zhu ◽  
Wenqian Xu ◽  
Eric Dooryhee ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
X Ray ◽  
Prediction Algorithms

X-ray powder diffraction and crystal structure prediction algorithms are used in synergy to establish the crystal structure of the eighth polymorph of ROY, form R05.

Frontiers between crystal structure prediction and determination by powder diffractometry

2008 ◽  
Vol 23 (S1) ◽  
pp. S5-S12 ◽  
Author(s):  
Armel Le Bail
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Structure Determination ◽  
Structure Prediction ◽  
Water Molecules ◽  
Crystal Structure Prediction ◽  
Large Intensity ◽  
Cell Parameters ◽  
Structure Solution ◽  
Diffraction Patterns

The fuzzy frontiers between structure determination by powder diffractometry and crystal structure prediction are discussed. The application of a search-match program combined with a database of more than 60 000 predicted powder diffraction patterns is demonstrated. Immediate structure solution (before indexing) is shown to be possible by this method if the discrepancies between the predicted crystal structure cell parameters and the actual ones are <1%. Incomplete chemistry of the hypothetical models (missing interstitial cations, water molecules, etc.) is not necessarily a barrier to a successful identification (in spite of inducing large intensity errors), provided the search-match is made with chemical restrictions on the elements present in both the virtual and experimental compounds.

The X-Ray Powder Diffraction Patterns and Crystal Structure for Al2M3Y(M=Cu, Ni)

2014 ◽  
Vol 950 ◽  
pp. 48-52
Author(s):  
De Gui Li ◽  
Ming Qin ◽  
Liu Qing Liang ◽  
Zhao Lu ◽  
Shu Hui Liu ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Hexagonal Structure ◽  
Argon Atmosphere ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Arc Melting ◽  
Diffraction Patterns

The Al2M3Y(M=Cu, Ni) compound was synthesized by arc melting under argon atmosphere. The high-quality powder X-ray diffraction data of Al2M3Y have been presented. The refinement of the X-ray diffraction patterns for the Al2M3Y compound show that the Al2M3Y has hexagonal structure, space groupP6/mmm(No.191), with a = b = 5.1618(2) Å, c = 4.1434(1) Å,V= 95.6 Å3,Z= 1,ڑx= 5.7922 g/cm3,F30= 155.5(0.0057, 34), RIR = 2.31 for Al2Cu3Y, and with a = b = 5.0399(1) Å, c = 4.0726(1) Å,V= 89.59 Å3,Z= 1,ڑx= 5.9118 g/cm3,F30= 135.7(0.0072, 30), RIR = 2.54 for Al2Ni3Y.

Characterization of Complicated New Polymorphs of Chlorothalonil by X-ray Diffraction and Computer Crystal Structure Prediction

2004 ◽  
Vol 126 (22) ◽  
pp. 7071-7081 ◽  
Author(s):  
Maryjane Tremayne ◽  
Leanne Grice ◽  
James C. Pyatt ◽  
Colin C. Seaton ◽  
Benson M. Kariuki ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
X Ray Diffraction ◽  
X Ray

scholarly journals Machine Learning-based Crystal Structure Prediction for X-Ray Microdiffraction

2018 ◽  
Vol 24 (S2) ◽  
pp. 144-145 ◽  
Author(s):  
Yuta Suzuki ◽  
Hideitsu Hino ◽  
Yasuo Takeichi ◽  
Takafumi Hawai ◽  
Masato Kotsugi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Machine Learning ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
X Ray

A Rietveld-analysis program for X-ray powder spectro-diffractometry

1999 ◽  
Vol 14 (2) ◽  
pp. 106-110 ◽  
Author(s):  
Yanan Xiao ◽  
Shinjiro Hayakawa ◽  
Yohichi Gohshi ◽  
Masaharu Oshima ◽  
Fujio Izumi ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Powder Diffraction ◽  
Absorption Edge ◽  
Rietveld Method ◽  
Rietveld Analysis ◽  
Anomalous Scattering ◽  
Analysis Program ◽  
X Ray ◽  
Diffraction Patterns ◽  
X Ray Absorption

In order to exploit X-ray powder spectro-diffractometry, the program RIETAN-97ß for refining crystal structure and lattice parameters by the Rietveld method was modified extensively. The resulting software can be used to refine anomalous scattering factors, fr and fi, for specified crystallographic sites near the X-ray absorption edge of a particular element. The effectiveness of the modified software was tested by using powder diffraction patterns simulated by the original RIETAN-97ß software and a series of measured powder diffraction patterns of Fe3O4 with incident X-ray energies near the absorption edge of iron.

scholarly journals Powder diffraction and crystal structure prediction identify four new coumarin polymorphs

2017 ◽  
Vol 8 (7) ◽  
pp. 4926-4940 ◽  
Author(s):  
Alexander G. Shtukenberg ◽  
Qiang Zhu ◽  
Damien J. Carter ◽  
Leslie Vogt ◽  
Johannes Hoja ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Powder Diffraction ◽  
Structure Prediction ◽  
Prediction Method ◽  
Crystal Structure Prediction ◽  
Free Energies ◽  
Structure Prediction Method

Crystal structures of four new coumarin polymorphs were solved by crystal structure prediction method and their lattice and free energies were calculated by advanced techniques.

scholarly journals Crystal structure prediction of organic pigments

2006 ◽  
Vol 62 (a1) ◽  
pp. s79-s79
Author(s):  
N. Panina ◽  
F. Leusen ◽  
R. Van de Ven ◽  
F. Janssen ◽  
P. Verwer ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Structure Prediction ◽  
Crystal Structure Prediction ◽  
Organic Pigments
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