The Novel Method for Fine Structural Analysis by the MEM Combined with Rietveld Analysis.

本课题旨在建立一种基于最大熵法（MEM）和Rietveld分析相结合的精细结构分析新方法。该方法采用Rietveld分析法对复杂的粉末图案进行反卷积，以估计MEM分析中每个反射的综合强度。最后，我们可以从功率衍射数据中得到包含键合性质等信息的精细电荷密度。这项工作的目的是扩展结构分析的潜力，然后通过利用Rietveld分析对粉末模式拟合的优点改进MEM的能力，为“新晶体学”打开一扇门。结果表明，该方法已成功地应用于许多富勒烯相关材料、高温超导体等。其中，金属富勒烯（Y@C_<82>）结构分析的成功是本项目最大的成果之一。这项研究发表在《自然》杂志（377(1995)46-49）上，并在一些报纸上进行了报道。MEM与Rietveld分析相结合将成为复杂材料结构研究的关键方法。

This research project had been carried out to develop the novel method of fine structural analysis using the Maximum Entropy Method (MEM) combined with Rietveld analysis. This method employs the Rietveld Analysis to deconvolute the complicated powder pattern to estimate integrated intensities of each reflections for the MEM analysis. As the final result, we can obtain the fine charge density including information of bonding nature etc.from power diffraction data. The aim of this work was to extend a potential of the structural analysis and then to open a door to "new crystallography" by the improvement of an ability of MEM using a merit of the Rietveld analysis for the powder pattern fitting. Consequently, the work was achieved sucessfully and the present method has been already applied to many fullerene-related materials, high-Tc superconductors and etc. Among them, the sucess of the structural analysis of metallofullerene, Y@C_<82>, was one of the greatest results in this project. This has been published in Nature (377 (1995) 46-49) and reported in some news papers.The MEM combined with Rietveld analysis shall become key method of the structural studies of complicated materials.