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  Jauch, W. ; Reehuis, M.: Electron density distribution in paramagnetic chromium: A gamma-ray diffraction study. Physical Review B 73 (2006), p. 085102/1-8

10.1103/PhysRevB.73.085102

Abstract:
High-accuracy single-crystal structure factors, complete up to sin/Å have been measured from paramagnetic chromium at 333 K using 316.5-keV gamma radiation. A detailed description of the electron density distribution is derived in terms of a multipolar atomic deformation model. There is pronounced charge asphericity in the valence region arising from preferential occupancy of the t2g subshell. The 3d charge distribution is contracted by 12.6% relative to the free atom, in accordance with magnetic synchrotron x-ray and neutron measurements. By contrast, the atomic crystal scattering factor deduced from experiment is found to be in contradiction with earlier experimental and theoretical work. Achievement of a reliable Debye-Waller factor is of vital importance in this context. There is no evidence for an anharmonic term in the atomic potential. Real-space and energetic features of the charge density topology are used to characterize the directed metallic bonds. Special attention is paid to the form factor approximation in diffraction data analysis.