Toward Polaritonic\nMolecular Orbitals for Large Molecular\nSystems

A comprehensive understanding of electron–photon\ncorrelation\nis essential for describing the reshaping of molecular orbitals in\nquantum electrodynamics (QED) environments. The strong coupling QED\nHartree–Fock (SC-QED-HF) theory tackles these aspects by providing\nconsistent molecular orbitals in the strong coupling regime. The previous\nimplementation, however, has significant convergence issues that limit\nthe applicability. In this work, we introduce two second-order algorithms\nthat significantly reduce the computational requirements, thereby\nenhancing the modeling of large molecular systems in QED environments.\nFurthermore, the implementation will enable the development of correlated\nmethods based on a reliable molecular orbital framework as well as\nmulti-level methodologies able to model the inclusion of solvent effects\nin this kind of complex systems.