Fourth-Order Algebraic Diagrammatic Construction for Electron Detachment and Attachment: The IP- and EA-ADC(4) Methods

We present a non-Dyson
fourth-order algebraic diagrammatic construction
formulation of the electron propagator, featuring the distinct IP-
and EA-ADC(4) schemes for the treatment of ionization and electron
attachment processes. The algebraic expressions have been derived
automatically using the intermediate state representation approach
and implemented in the Q-Chem quantum-chemical program package.
The performance of the novel methods is assessed with respect to high-level
reference data for ionization potentials and electron affinities of
closed- and open-shell systems. While only minor improvements over
the corresponding third-order methods are observed for one-hole ionization
and one-particle electron attachment processes from closed-shell systems
(MAEIP‑ADC(4) = 0.27 eV and MAEEA‑ADC(4) = 0.05 eV), a significantly enhanced performance is found in case
of open-shell reference states (MAEIP‑ADC(4) = 0.11
eV and MAEEA‑ADC(4) = 0.02 eV). A particularly appealing
feature of the novel methods is their accurate treatment of satellite
transitions. For closed-shell reference states, we obtain accuracies
of MAEIP‑ADC(4) = 0.81 eV and MAEEA‑ADC(4) = 0.27 eV, while in case of open-shell reference states, mean absolute
errors of MAEIP‑ADC(4) = 0.15 eV and MAEEA‑ADC(4) = 0.27 eV are found.