Electron density distribution from powder diffraction experiment

A recent progress of the Maximum Entropy Method to obtain a precise electron density distribution from X-ray powder diffraction data is reviewed. Results for rutile (TiO2), fcc metal Al and hcp metal Mg are given. In rutile case, apical and equatorial bonds of TiO6 octahedra are visible in the MEM density map, which is the electron density map obtained by the Maximum Entropy Method. The nuclear density distribution of rutile is also shown, in which it is seen that the nuclear is localized only on the atomic site. The MEM map of Al looks to be well described by the nearly free electron model. On the other hand, in the case of Mg, the small electron density peaks are seen between three Mg atoms on the basal plane, on which electronic layers are formed in this substance. (author)