THE ELECTRON-DENSITY DISTRIBUTION IN BE METAL OBTAINED FROM SYNCHROTRON-RADIATION POWDER DATA BY THE MAXIMUM-ENTROPY METHOD

The nature of the bonding in Be metal was studied by investigating the MEM map, which is the electron density distribution obtained by the Maximum-Entropy Method. In order to avoid extinction effects, 19 Bragg reflections were measured by a new powder-diffraction experiment that utilizes Synchrotron Radiation as an incident X-ray and an Imaging Plate as detector. The experiment was carried out at the Photon Factory BL6A2. In spite of the limited number of reflections used in the MEM analysis, the electron density distribution of Be was obtained accurately and reliably. The structure factors for umneasured reflections were calculated and compared with the values observed by Larsen and Hansen [Acta Cryst. B 40, 169 (1984)]. The agreement is very good. Furthermore, the MEM map revealed that Be metal forms an electronic layer in the shape of a honeycomb that is parallel to the basal plane.