Electron Propagator Self-Energies versus Improved GW100 Vertical Ionization Energies

Ab initio electron propagator (EP) methods
that
are free of adjustable parameters in their self-energy formulae and
in the generation of their orbital bases have been applied to the
calculation of the lowest vertical ionization energies (VIEs) of the
GW100 set. An improved set of standard results accompanied by irreducible
representation assignments has been produced indirectly with coupled-cluster
singles and doubles plus perturbative triples, i.e., CCSD­(T), total
energy differences at initial-state geometries reoptimized (in 28
cases) with the largest applicable point groups. The best compromises
of accuracy and efficiency belong to a new generation of EP self-energies,
several members of which may be derived from an intermediately normalized,
Hermitized super-operator metric. The following diagonal self-energy
methods are optimal: opposite-spin non-Dyson second order (os-nD-D2),
approximately renormalized partial third order (P3+), approximately
renormalized quasiparticle third order (Q3+), and non-Dyson approximately
renormalized linear third order version B (nD-L3+B). Their mean absolute
errors (MAEs) in electron volts and arithmetic scaling factors expressed
in terms of occupied (O) and virtual (V) orbital dimensions are, respectively,
(0.18, OV2), (0.14, O2V3), (0.15,
O2V3), and (0.11, OV4). The 0.06
eV MAE for the non-diagonal, sixth-power (O2V4) Brueckner doubles, triple-field operator (BD-T1) EP method is exceeded
by the 0.1 eV MAE with respect to experiments in seventh-power, ΔCCSD­(T)
calculations and indicates that BD-T1 may serve as a direct, spin-symmetry-conserving
alternative in the generation of standard results for VIEs of larger,
closed-shell molecules.