2003/07/29 by Kyungwha Park, Mark R. Pederson, C. Stephen Hellberg
Biochemistry, Genetics and Molecular Biology · Materials Science · Physics and Astronomy · #Electron Spin Resonance Studies #Magnetism in coordination complexes #Porphyrin and Phthalocyanine Chemistry #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.69.014416
arxiv created 2003/07/29 · openalex publication_date 2004/01/26 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
Most experimental properties of the single-molecule magnet Mn12 acetate have been successfully explained by the assumption that Mn12 acetate has an effective ground-state spin of S=10. However, the effect of the low-lying excited manifolds caused by interactions between Mn spins has not been well understood. To investigate the features of the low-lying excited manifolds, the intramolecular exchange interactions are calculated using density-functional theory (DFT). With the calculated exchange parameters, the energy gap between the S=10 ground state and the first-excited-state manifold is calculated by diagonalization of the Heisenberg Hamiltonian. The upper limit on the energy gap is about 40.5 K which is likely to be overestimated due to an incomplete treatment of the Coulomb potential within DFT. It is found that there are several S=9 low-energy excited-state manifolds above the S=10 ground-state manifold. The magnetic anisotropy barriers for the low-lying spin excitations are calculated using DFT. Based on the calculations, it is found that the anisotropy barriers for the low-lying excited manifolds are approximately the same as that for the ground-state manifold.