Heme-based metalloproteins play a central role in respiration by transporting and storing oxygen, a function that is inhibited by carbon monoxide. Density-functional theory has been unable to provide a complete description of the binding of these ligands to heme's central iron atom, predicting an unrealistically high relative affinity for carbon monoxide. Here, we solve this problem using dynamical mean-field theory in combination with linear-scaling density-functional theory, thus allowing for a simultaneous description of crucial quantum entanglement and protein discrimination effects in the ground-state of the oxygen-heme complex. By simulating the binding process within a 1,000-atom quantum-mechanical model of the myoglobin metalloprotein, we obtain a significantly improved description of its spectroscopic and energetic observables.

Abstract