Electronic States and Geometrical Structures of Hubbard Clusters with an Impurity
The relative stability and electronic excitation spectrum of three, four, and five site clusters is studied in the context of Hubbard model. Electron correlation is found to decrease the cohesive energy appreciably in the half-filled case. Planar geometries with a lower symmetry (pure cluster) or a large number of impurity bonds (impurity clusters) are found to be relatively stable. Noninteracting ground state is found to differ from the single particle ground state obtained by filling single particle states using the Pauli principle.
KeywordsGround State Energy Hubbard Model Cohesive Energy Single Particle State Pauli Principle
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