Exact solution of the Hubbard model for a four-center tetrahedral cluster
- 15 August 1984
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review B
- Vol. 30 (4) , 1695-1699
- https://doi.org/10.1103/physrevb.30.1695
Abstract
The eigenvalues of a Hubbard Hamiltonian for a four-center tetrahedral cluster are calculated exactly. Full use is made of the symmetry of the problem, which is analyzed for an arbitary number of electrons, . Comparison is made with the phenomenological Hund's-rule predictions for the ground states. The diversity of the low-energy states is surprising: magnetic and nonmagnetic solutions, single and degenerate representations, accidental degeneracies, and symmetry crossovers are all found for the ground states. Implications for three-dimensional lattices are discussed.
Keywords
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