The electron density of beryllium derived from 0·12 Å γ-ray diffraction data

A large set of structure factors for beryllium has been measured with a 0.12 Å γ-ray diffractometer. The present data are in good agreement with other recent X-ray and γ-ray diffraction measurements. Extinction was significant though not very strong. Deformation density maps confirm that the bonding goes through the tetrahedral holes of the hexagonal close-packed structure. Comparisons with band-structure calculations indicate that the local-density approximation to the density functional theory is valid for beryllium. The quality of the data, combined with the earlier experimental results, is sufficient to demonstrate that the structure factors are sensitive to the valence electron hybridization even at high momentum transfer [(sin θ)/ λ > 0.75 Å^-1]. Core electron deformation is a much smaller effect.