A charge density study of copper by γ-ray diffractometry on imperfect single crystals

19 absolute atomic scattering factors were measured for imperfect copper single crystals with an accuracy of the order of ±0.05 electrons for reflections with sin θ/λ ≤ 0.7 Å^-1. This data set is of significantly higher accuracy than those measured earlier with X-rays for imperfect single crystals. The experimental form factors for low momentum transfer are significantly smaller than the free-atom values. The corresponding deformation density shows a small pile up of charge between nearest-neighbour atoms. At the present level of experimental accuracy, none of the available band-structure calculations provides a satisfactory description of the measured form factors over the whole range of momentum transfer where effects due to bonding can be expected.