日本結晶学会誌
Online ISSN : 1884-5576
Print ISSN : 0369-4585
ISSN-L : 0369-4585
53 巻, 4 号
選択された号の論文の16件中1~16を表示しています
連載企画 有機粉末構造解析をはじめよう!
  • 池田 卓史
    2011 年 53 巻 4 号 p. 231-239
    発行日: 2011/08/31
    公開日: 2011/09/15
    ジャーナル フリー
    The indexing process, that is determination of unit-cell parameters, is the first important stage of the crystal structure determination from powder diffraction data (SDPD). Accurate Bragg positions (2θ or d values) of 10∼20 peaks picked up by peak-search from low 2θ angle side are indispensable for determination of lattice constants with hkl indices. Subsequently, space group can be estimated according to systematic absences based on obtained lattice constants. Integral intensities of each reflection are tentatively extracted by the whole powder pattern fitting i.e. the Le Bail or Pawley methods. Crystal structure of small organic molecule can be solved by the direct method or the charge flipping algorithm. In this report, the brief summary about indexing and whole pattern fitting was described. Furthermore, some practical examples of SDPD of small organic molecules by the direct method (EXPO2009) and the charge flipping (Superflip) were demonstrated.
  • 西堀 英治
    2011 年 53 巻 4 号 p. 240-248
    発行日: 2011/08/31
    公開日: 2011/09/15
    ジャーナル フリー
    The crystal structure determination from powder diffraction (SDPD) has attracted wide interests for its huge potential to accelerate a design, synthesis, and characterization of the materials in the fields of nano- and bio- technologies. One of the most important progresses of the SDPD is the development of the direct-space strategy. In this report, SDPD by direct-space strategy has been described. Fundamental aspects of the strategy have been demonstrated with some examples. Global optimization methods within direct-space strategy such as Grid Search, Simulated Annealing, and Genetic Algorithm have been described including detailed methodologies.
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