Source-linked AI summary
The electronic complexity of the ground-state of the FeMo cofactor of nitrogenase as relevant to quantum simulations
Zhendong Li, Junhao Li, Nikesh S. Dattani, C. J. Umrigar, Garnet Kin-Lic Chan
TL;DR
The FeMoco active space used in a recent quantum-simulation study does not represent the cofactor’s ground-state electronic structure, complicating conclusions about its classical simulation complexity. The paper compares classical calculations on that model and constructs a different active space with open-shell character; it concludes that the prior model’s quantum resource estimates are probably reasonable, while its classical complexity is misleading.
Problem
The FeMoco active space used in a recent quantum-simulation study lacks the representative ground-state electronic structure needed to assess the cluster’s classical simulation complexity.
Source: p. 1Method
The authors compare classical electronic-structure calculations on the prior model and construct a 113-electron, 76-orbital active space from Fe, S, Mo, C, and bonding ligand orbitals.
Source: pp. 1–2Results
The prior (54e,54o) model has no open shells and supports accurate ground-state energies from standard classical methods, unlike the open-shell character expected for FeMoco.
Source: pp. 1–2Takeaways & Limitations
The new active space captures FeMoco’s basic open-shell qualitative character and may serve as a benchmark for classical and quantum resource estimates.
Source: p. 2The ground-state character affects adiabatic state-preparation cost, which the prior study leaves open; other factors such as environment convergence and protonation also require consideration.
Source: p. 2
Abstract
from arXiv · showhide
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.