We consider quantum tunneling of magnetization (QTM) in single-molecule magnets (SMMs) possessing idealized C 3 symmetry. We do so by mapping the spectrum of a Mn III 3 SMM obtained via diagonalization of a multispin (three s = 2 spins) Hamiltonian onto that of a giant-spin model with spin S = 6. Rotation of the easy axes of the Mn III atoms away from the C 3 axis leads to the emergence of theÔ 3 4 (≡1/2[Ŝ z ,Ŝ 3 + +Ŝ 3 − ]) operator in the giant-spin model. This unfreezes odd-k QTM resonances

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... nd generates threefold patterns of Berry-phase interference minima in all resonances, including k = 0, which shifts from zero longitudinal field.