Multireference protonation energetics of a dimeric model of nitrogenase iron-sulfur clusters

Understand

Characterizing the electronic structure of the iron--sulfur clusters in nitrogenase is necessary to understand their role in the nitrogen fixation process.

• One challenging task is to determine the protonation state of the intermediates in the nitrogen fixing cycle.
• Here, we use a dimeric iron--sulfur model to study relative energies of protonation at C, S or Fe.
• Using a composite method based on coupled cluster and density matrix renormalization group energetics, we converge the relative energies of four protonated configurations with respect to basis set and correlation level.