Total energies from GW calculations

The possibilities of obtaining accurate total energies from GW calculations at Various levels of self-consistency are investigated. In the conserving approximation known as the fully self-consistent GW approach there is no am biguity in calculating the total energy, and the results for the electron a s compare well with those of accurate Monte Carlo calculations. We demonstr ate how to obtain chemical potentials and total energies of similar accurac y from partially self-consistent (GW(0)) calculations.