High-Resolution Compton Scattering Study of Li: Asphericity of the Fermi Surface and Electron Correlation Effects

We present high-resolution Compton scattering spectra from Li single crystals together with corresponding highly accurate local-density-approximation (LDA) based computations. The data are analyzed to obtain Fermi surface radii along the three principal symmetry directions; the maximum measured anisotropy is found to be $\left(4.6\pm 1.0\right)\%$. Comparisons between the measured and computed spectra clearly reveal departures from the conventional one-particle LDA picture of the ground state momentum density of the electron gas. This study establishes the potential of Compton scattering as a tool for investigating Fermiology-related issues in materials.