Unified description of ground and excited states of finite systems: The self-consistent GW approach

GW calculations with a fully self-consistent Green's function G and screened interaction W-based on the iterative solution of the Dyson equation-provide a consistent framework for the description of ground- and excited-state properties of interacting many-body systems. We show that for closed-shell systems self-consistent GW reaches the same final Green's function regardless of the initial reference state. Self-consistency systematically improves ionization energies and total energies of closed-shell systems compared to G ₀W ₀ based on Hartree-Fock and (semi)local density-functional theory. These improvements also translate to the electron density, as exemplified by an improved description of dipole moments, and permit us to assess the quality of ground-state properties such as bond lengths and vibrational frequencies.