“…7,8). Numerous experiments on Mn 12 performed since 1996 uncovered a number of other interesting phenomena, such as memory effects, 9 non-exponential relaxation, 9,10,11 and a peculiar crossover between thermal and quantum behavior 12,11 predicted by theory. 13,14,15,16,17,18,19,20,21,22,23,24 Uniaxial spin Hamiltonian, in the field parallel to the anisotropy axis, H = −DS 2 z − H z S z , has pairs of degenerate levels for H z = kD, k = 0, ±1, ±2, .…”