  We report that a recent active space model of the nitrogenase FeMo cofactor,
proposed in the context of quantum simulations, is not representative of the
electronic structure of the FeMo cofactor ground-state. Although quantum
resource estimates, outside of the cost of adiabatic state preparation, will
not be much affected, conclusions should not be drawn from the complexity of
classical simulations of the electronic structure of this system in this active
space. We provide a different model active space for the FeMo cofactor that
contains the basic open-shell qualitative character, which may be useful as a
benchmark system for making classical and quantum resource estimates.
