The $GW$ approximation is a cornerstone of many-body perturbation theory for computing single-particle excitations, yet it can fail qualitatively in strongly correlated systems where the single-reference picture becomes inadequate. To overcome this limitation, we develop a diagrammatic route to multireference $GW$ (MR-$GW$) from an interacting active-space reference, treating strong correlation nonperturbatively and the residual interaction through dynamical screening at the multireference random phase approximation level. Because the conventional diagrammatic self-energy expansion no longer applies, we define a practical one-shot MR-$GW$ approximation within a generalized diagrammatic framework, recovering standard $GW$ as a special case. Applications to prototypical correlated atoms and molecules show that the interacting active-space reference captures multiconfigurational satellite structures poorly described by single-reference $GW$, while dynamical screening generally improves the satellite energies as well as the leading ionization and electron-attachment energies. This work opens a diagrammatic route to Green’s-function methods that combine nonperturbative strong correlation with dynamical screening.

Close

PrevNext

View figure in article

• Electronic structure of atoms & molecules
• Green's function methods