MEM-based structure-refinement system REMEDY and its applications

F. Izumi; S. Kumazawa; T. Ikeda; W. Z. Hu; A. Yamamoto; K. Oikawa

doi:10.4028/www.scientific.net/msf.378-381.59

MEM-based structure-refinement system REMEDY and its applications

F. Izumi, S. Kumazawa, T. Ikeda, W. Z. Hu, A. Yamamoto, K. Oikawa

Research output: Contribution to journal › Conference article › peer-review

78 Citations (Scopus)

Abstract

A Rietveld-analysis program RIETAN was combined with MEED for a maximum-entropy method (MEM) to grow into an integrated software REMEDY. At first, 'observed' structure factors, F_o, estimated after Rietveld analysis are analyzed by the MEM to give electron/nuclear densities biased by a structural model. Then, we evaluate structure factors, F_c(MEM), by the Fourier transform of the densities and fit the whole powder pattern calculated from the F_c(MEM) data to the observed one to refine parameters irrelevant to the structure. F_o data obtained in such a manner are analyzed again by the MEM. MEM analysis and whole-pattern fitting are alternately repeated until R factors in the pattern fitting no longer decrease. REMEDY was utilized to investigate (a) positional disorder of K⁺ ions interlayered in K_xTi_2-x/3Li_x/3O₄, (b) atomic arrangement of K clusters in K-type LTA, and (c) nuclear/electron-density distribution in HgBa₂CuO_4+δ.

Original language	English
Pages (from-to)	59-64
Number of pages	6
Journal	Materials Science Forum
Volume	378-381
Issue number	I
DOIs	https://doi.org/10.4028/www.scientific.net/msf.378-381.59
Publication status	Published - 2001 Jan 1
Externally published	Yes
Event	7th European Powder Diffraction Conference - Barcelona, Spain Duration: 2000 May 20 → 2000 May 23

Keywords

Electron density
Layered compound
Maximum-entropy method
Nuclear density
Superconductor
Whole-pattern fitting
Zeolite

ASJC Scopus subject areas

Materials Science(all)
Condensed Matter Physics
Mechanics of Materials
Mechanical Engineering

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abstract = "A Rietveld-analysis program RIETAN was combined with MEED for a maximum-entropy method (MEM) to grow into an integrated software REMEDY. At first, 'observed' structure factors, Fo, estimated after Rietveld analysis are analyzed by the MEM to give electron/nuclear densities biased by a structural model. Then, we evaluate structure factors, Fc(MEM), by the Fourier transform of the densities and fit the whole powder pattern calculated from the Fc(MEM) data to the observed one to refine parameters irrelevant to the structure. Fo data obtained in such a manner are analyzed again by the MEM. MEM analysis and whole-pattern fitting are alternately repeated until R factors in the pattern fitting no longer decrease. REMEDY was utilized to investigate (a) positional disorder of K+ ions interlayered in KxTi2-x/3Lix/3O4, (b) atomic arrangement of K clusters in K-type LTA, and (c) nuclear/electron-density distribution in HgBa2CuO4+δ.",

keywords = "Electron density, Layered compound, Maximum-entropy method, Nuclear density, Superconductor, Whole-pattern fitting, Zeolite",

author = "F. Izumi and S. Kumazawa and T. Ikeda and Hu, {W. Z.} and A. Yamamoto and K. Oikawa",

year = "2001",

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AU - Izumi, F.

AU - Kumazawa, S.

AU - Ikeda, T.

AU - Hu, W. Z.

AU - Yamamoto, A.

AU - Oikawa, K.

PY - 2001/1/1

Y1 - 2001/1/1

N2 - A Rietveld-analysis program RIETAN was combined with MEED for a maximum-entropy method (MEM) to grow into an integrated software REMEDY. At first, 'observed' structure factors, Fo, estimated after Rietveld analysis are analyzed by the MEM to give electron/nuclear densities biased by a structural model. Then, we evaluate structure factors, Fc(MEM), by the Fourier transform of the densities and fit the whole powder pattern calculated from the Fc(MEM) data to the observed one to refine parameters irrelevant to the structure. Fo data obtained in such a manner are analyzed again by the MEM. MEM analysis and whole-pattern fitting are alternately repeated until R factors in the pattern fitting no longer decrease. REMEDY was utilized to investigate (a) positional disorder of K+ ions interlayered in KxTi2-x/3Lix/3O4, (b) atomic arrangement of K clusters in K-type LTA, and (c) nuclear/electron-density distribution in HgBa2CuO4+δ.

AB - A Rietveld-analysis program RIETAN was combined with MEED for a maximum-entropy method (MEM) to grow into an integrated software REMEDY. At first, 'observed' structure factors, Fo, estimated after Rietveld analysis are analyzed by the MEM to give electron/nuclear densities biased by a structural model. Then, we evaluate structure factors, Fc(MEM), by the Fourier transform of the densities and fit the whole powder pattern calculated from the Fc(MEM) data to the observed one to refine parameters irrelevant to the structure. Fo data obtained in such a manner are analyzed again by the MEM. MEM analysis and whole-pattern fitting are alternately repeated until R factors in the pattern fitting no longer decrease. REMEDY was utilized to investigate (a) positional disorder of K+ ions interlayered in KxTi2-x/3Lix/3O4, (b) atomic arrangement of K clusters in K-type LTA, and (c) nuclear/electron-density distribution in HgBa2CuO4+δ.

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KW - Maximum-entropy method

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KW - Superconductor

KW - Whole-pattern fitting

KW - Zeolite

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