“…At the same time, the applicability of standard wave function-based method is very limited, mainly due to unfavorable computational scaling of multireference approaches. Geminal-based methods are a promising alternative to conventional quantum chemistry models, providing a more compact representation of the correlated wave function. − Commonly used examples are the wave function classes based on the Antisymmetric Product of 1-reference orbital Geminal (AP1roG), , also known as pair Coupled Cluster Doubles (pCCD), the Antisymmetrized Product of Strongly orthogonal Geminals (APSG), the Generalized Valence Bond (GVB), and their orbital optimized variants (for a recent review, see ref ). ,− Combined with a reliable a posteriori correction to account for the missing dynamic correlation effects, − they allow us to model electron correlation effects effectively and in a balanced way . Except for perturbation-based approaches, which might break size-extensivity, these geminal-based models can be upscaled to model OPV-devices.…”