To test the feasibility of local spin theory of Davidson and Clark for ferrodoxin clusters, the models [Fe2S2(SR)4]2− (R=—H, —CH3) are chosen for evaluation. This purpose is realized by calculating the local spin expectation values 〈S A·S B〉, 〈S A 2 〉, and m A and discussing the connection between these expected values and the Heisenberg spin model (HSM) and the Noodleman broken-symmetry approach. In practical calculation, the spin-unrestricted Hartree-Fock (UHF) and spin-polarized density functional theory (DFT) are used and the calculational qualities of these two methods are also discussed. In addition, the theoretical magnetic coupling constants J AB of these models are calculated by various computational schemes for comparison with both theoretical and experimental results previously reported.