Compton Profile Study and Electron Momentum Density Reconstruction in Hexagonal Mg

Abstract

Four directional Compton profiles (CPs) of a hexagonal magnesium single crystal have been measured with high momentum resolution (0.12 a.u.) using 115.6 keV synchrotron radiation in SPring-8. Experimental CP anisotropies were compared with augmented plane waves (APW), Korringa–Kohn–Rostocker (KKR), and the latest density functional theory (DFT) band structure calculations. In order to reconstruct the full three-dimensional valence electron momentum density distribution, maximum entropy method (MEM) was applied. 3D electron momentum densities obtained using MEM were compared (after appropriate integration) with 2D electron momentum density reconstructed using Cormack's method. MEM has proved its advantage as a technique for reconstructing density distributions when initial information is insufficient and noisy. The 3D valence electron momentum density of hexagonal Mg was successfully reconstructed using as few as four experimental or five theoretical Compton profiles. As is shown, despite a clear anisotrop...