STRUCTURE DETERMINATION BY ELECTRON CRYSTALLOGRAPHY USING BOTH MAXIMUM-ENTROPY AND SIMULATION APPROACHES

Ab initio structure determination and refinement from electron diffrac tion data is not a widely used technique in structural science because of the inaccuracies inherent in the process of intensity measurement and because the relative sparseness of the data sets collected makes t he structures hard to solve; there are also problems of verifying the correctness of the results. In this paper, the techniques of model bui lding from electron diffraction data were employed to solve the struct ure. In addition, an ab initio solution of the structure of [9,9'-bian thryl]-10-carbonitrile is presented using a routine application of the maximum-entropy method combined with likelihood evaluation employing 150 unique diffraction intensities. The structure thus determined was obtained independently of the model-building studies. The agreement be tween the two methods is excellent and both agree with a single-crysta l X-ray study on the same material. In addition, the high-resolution i mages agree with the images calculated from the model and with the pot ential maps after correction for the transfer function and dynamic sca ttering.