<i>Ab initio</i> structure determination of monoclinic 2,2-dihydroxymethylbutanoic acid from synchrotron radiation powder diffraction data: combined use of direct methods and the Monte Carlo method

Tanahashi, Yusaku; Nakamura, Hisayoshi; Yamazaki, Shoko; Kojima, Yoshitaka; Saito, H; Ida, Takashi; Toraya, Hideo

doi:10.1107/s0108768100018905

Cited by 9 publications

(3 citation statements)

References 23 publications

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“…Two oxygen and five carbon atoms among the ten nonhydrogen atoms were first derived by the direct method. The missing two oxygen and one carbon atoms were found by the present procedure without applying constraints to their relative positions (Tanahashi et al, 2001).…”

Section: Structure Determination Of 22-dihydroxymethylbutanoic Acid mentioning

confidence: 95%

The Monte Carlo method for finding missing atoms in solving crystal structures from powder diffraction data without applying a rigid-body approximation

et al. 2001

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The Monte Carlo method is applied to finding missing atoms in solving inorganic crystal structures without applying a rigid-body approximation. Whole powder patterns of α-SiO2 and Mg2SiO4 were used for testing a procedure. Four atoms among the six in the asymmetric unit of Mg2SiO4 could be found in the present analysis. The use of well-refined profile parameters enhanced the frequency of correct structure configurations in the Monte Carlo search. Utilizing structural information available for constructing a trial configuration is also considered to be important for efficiently searching the structure solution. A procedure for assignment of equivalent positions to respective atoms is presented. The method can be used as a powerful tool for finding missing atoms in a partially solved structure. A histogram of weighted reliability index in Monte Carlo calculations is very informative for evaluating the performance of the method. ©

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Section: Structure Determination Of 22-dihydroxymethylbutanoic Acid mentioning

confidence: 95%

The Monte Carlo method for finding missing atoms in solving crystal structures from powder diffraction data without applying a rigid-body approximation

et al. 2001

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“…The basis of the direct-space strategy for structure solution is to find the trial crystal structure corresponding to lowest R-factor and is equivalent to exploring a hypersurface R(Γ) to find the global minimum, where Γ represents the set of variables that define the structure. In principle, any technique for global optimization may be used to find the lowest point on the R(Γ) hypersurface, and much success has been achieved in using Monte Carlo/simulated annealing 16, [19][20][21][22][23][24][25][26][27][28] and genetic algorithm [29][30][31][32][33][34][35][36] methods in this field. In addition, grid search [37][38][39][40][41] and differential evolution 42 minations of organic molecular solids from powder diffraction data have used the direct-space strategy, although we note that there have also been a number of successful structure determinations of such materials using the traditional approach.…”

Section: Structure Determination From Powder Diffraction Datamentioning

confidence: 99%

Structural Characterization of Industrially Relevant Polymorphic Materials from Powder Diffraction Data

Harris

Cheung

2003

Org. Process Res. Dev.

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To fully characterize a polymorphic system, it is necessary to know the structural properties of all polymorphs formed by the molecule of interest. Traditionally, single-crystal X-ray diffraction techniques have been used for this purpose, although different polymorphic forms of a given molecule can differ significantly in crystal quality and in many cases only one or a few of the polymorphs yield single crystals that are suitable for investigation by single-crystal X-ray diffraction. Structural characterization of the other polymorphs must be carried out using powder X-ray diffraction. Fortunately, recent years have seen significant developments in techniques for determining crystal structures of molecular solids directly from powder diffraction data. This article highlights the current scope of these techniques and highlights some examples involving studies of polymorphic materials of industrial relevance.

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“…The basis of the direct-space strategy for structure solution is to find the trial crystal structure corresponding to lowest R-factor, and is equivalent to exploring a hypersurface R (Γ) to find the global minimum, where Γ represents the set of variables that define the structure. In principle, any technique for global optimization may be used to find the lowest point on the R (Γ) hypersurface, and much success has been achieved in using the MC, ,− simulated annealing, − and GA − ,− methods in this field. In addition, grid search − and differential evolution methods have also been employed.…”

Section: Introductionmentioning

confidence: 99%

New Opportunities for Structure Determination of Molecular Materials Directly from Powder Diffraction Data

Harris

2003

Crystal Growth & Design

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Although single crystal X-ray diffraction is a powerful technique for the determination of crystal and molecular structures, many solids can be prepared only as microcrystalline powders and therefore cannot be studied by single crystal diffraction techniques. For such materials, it is necessary to tackle structure determination using powder diffraction data. This article highlights recent developments in the opportunities for determining the crystal structures of molecular solids directly from powder diffraction data, focusing on the challenging structure solution stage of the structure determination process. In particular, the direct-space strategy for structure solution is highlighted, as this approach has led to significant recent advances in the structure determination of molecular solids. In the direct-space approach, a hypersurface defined by an appropriate powder diffraction R-factor is explored using global optimization techniques, and we focus on our development and application of Monte Carlo and genetic algorithm techniques within this field. Fundamental aspects are described, and examples are given to illustrate the application of the direct-space strategy to determine crystal structures of molecular materials.

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Ab initio structure determination of monoclinic 2,2-dihydroxymethylbutanoic acid from synchrotron radiation powder diffraction data: combined use of direct methods and the Monte Carlo method

Cited by 9 publications

References 23 publications

The Monte Carlo method for finding missing atoms in solving crystal structures from powder diffraction data without applying a rigid-body approximation

The Monte Carlo method for finding missing atoms in solving crystal structures from powder diffraction data without applying a rigid-body approximation

Structural Characterization of Industrially Relevant Polymorphic Materials from Powder Diffraction Data

New Opportunities for Structure Determination of Molecular Materials Directly from Powder Diffraction Data

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