Fig. 1. Molecular structure of (a) Mn12O12 (CH3COO)16(H2O)4, denoted as Mn12, and (b) energies of different MS projections in the ground spin multiplet of Mn12; an effective energy barrier Ueff = |D|S2 for spin inversion between MS = +10 and MS = –10 is derived from the spin Hamiltonian H = DSz2. Mn: yellow + green, O: red, and C: black; H is omitted for clarity.
