We optimized the geometry of Magnet 2 with finite thresholds: 10 -4 tolerance on the maximal gradient component (a.u.) and 10 -6 a.u. on the energy change; these thresholds are tighter that Q-Chem's default criteria for geometry optimization. The resulting geometry is slightly asymmetric within these criteria (for example, Cu-Cu distances are 3.416, 3.420, and 3.418 Å). Tighter thresholds lead to a symmetric geometry. C 3 symmetry point group has degenerate irreducible representations, which leads to issues with degenerate EOM solutions, as described in Ref. . To circumvent these problems, we used the lower symmetry geometry, which we also provide in the SI. In this non-symmetric geometry, the doublet states are split by only 2.5 cm -1 .