Classical quantum chemical solution of the FeMo-cofactor model to chemical accuracy and its implications.

Classical quantum chemistry methods achieve chemical accuracy in modeling the FeMo cofactor of nitrogenase, identifying several degenerate spin isomers within the model.

• Why it matters: Understanding the electronic structure of the FeMo cofactor is crucial for insights into nitrogenase function and for advancing quantum computing applications, but its complexity has limited accurate modeling.
• What they did: The study combines high-order coupled cluster and density matrix renormalization group calculations with an extrapolation protocol on a model of the FeMo cofactor, revealing multiple near-degenerate spin states.
• The result: The findings suggest that many features of the electronic landscape are preserved in more detailed nitrogenase models, highlighting the complexity of spectroscopic interpretations of its electronic structure.