Electron-electron interactions and the bandwidth of metals

Abstract
A calculation is presented of the self-energy of an electron from the screened exchange energy. Vertex corrections are included. They have a large effect upon the predictions of the width of the occupied energy bands. For aluminum the band-width is predicted to be 0.7 eV wider in the GW approximation compared to GWΓ which includes vertex corrections. Results using the GWΓ approximation are similar to those of the random-phase approximation.