First, we start by considering the electrostatic environments around the main candidate absorption sites for N2 in the 3U7Q nitrogenase, i.e., the Fe2 and Fe6 sites on the FeMoco unit. In Figure , the computed magnitudes of the OLEFs, i.e., Fz, pointing towards/away from these two sites are presented. From this quiver plot, it is apparent that the Fe2 site is surrounded by a strongly negative local electric field in all directions away from the core of the M-cluster. The magnitudes of the computed OLEFs range from +0.1 VÅ -1 to -1.6 VÅ -1 , depending on the precise direction and radius around the metal center considered.