Self-energy calculation of the hydrogen atom: Importance of the unbound states
We present the calculation of the self-energy of the isolated hydrogen atom within the GW approximation starting from the noninteracting Green's function constructed from the exact wave functions of the hydrogen atom. The error in the electron removal energy of the 1s state is found to be about 0.02 eV, which is much smaller than what one would expect. This small error is explained by the cancella