A study of charge density in beryllium

Abstract

Abstract The x-ray structure amplitudes for the 27 lowest-angle Bragg reflections of beryllium metal have been measured on an absolute scale. These can be used to deduce the charge density. The measured structure amplitudes are compared with those predicted both by the free atom Hartree-Foch wave functions and by a free electron orthogonalized plane wave model. For both models the predicted value for the lowest angle reflection is close to that observed, but the structure amplitudes of subsequent reflections given by the models are significantly greater than those observed. To account for these discrepancies a model of beryllium involving 2p-like tight binding functions is proposed.