DV-Xα法を用いた粉末Ｘ線構造解析のための初期位相の決定

山内彰史, 茅原静佳, 大賀俊輔, 石井知彦, 佐藤峰夫, 坂根弦太

初期位相の決定
We investigate X-ray structure analysis of the rare sugar monosaccharides whose crystal structures have never been reported up to now. General way for analyzing the crystal structure is done by using a monocrystalline sample in the case of the sugar molecule. However, some of the sugar molecular family can be obtained only in a powder crystal and or a very low quality of a single crystal. Therefore, the crystal structure analysis by means of the powder pattern X-ray structure analysis should be required. A powder X-ray structure analysis is done in the following five steps.
1. Powder X-ray diffraction experiment
2. Decision of Cell Parameter
3. Decision of system of crystal and space group
4. Decision of initial phase
5. Optimization of the internal crystal structure
The quality of an initial phase of the unknown compound is originally decided by the reciprocal space method. However, the molecular structure optimization in the case of an organic material is very easy and has a high accuracy, therefore, the technique of the real space method is often used for the structure analysis in the case of the organic compound. In this analysis, determination of an initial phase of the sugar molecule is the most important to solve the collect molecular structure by means of a real space method. In our study we obtain the optimized molecular structure by the application "WinMOPAC", then the electronic emergy level stability can be compared by a DV-Xα molecular orbital calculation.

Bulletin of the Society for Discrete Variational Xα

The Society for Discrete Variational Xα

24

1&2

124

128