Excitons in the strong coupling limit of the one-dimensional extended Hubbard model
Excitons in the strong coupling limit of the half-filled one-dimensional extended Hubbard model with 1/r interactions are studied. Unlike the situation for nearest neighbor interactions, where there is at most only one (doubly degenerate) bound state, a 1/r interaction results in an infinite number...
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| Format: | Journal article |
| Sprog: | English |
| Udgivet: |
2002
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| Summary: | Excitons in the strong coupling limit of the half-filled one-dimensional extended Hubbard model with 1/r interactions are studied. Unlike the situation for nearest neighbor interactions, where there is at most only one (doubly degenerate) bound state, a 1/r interaction results in an infinite number of doubly degenerate bound states. In the continuum limit the exciton states are one-dimensional hydrogenlike states, with binding energies ∼ 1/n2. The particle-hole separation grows rapidly with n as n2. The binding energies are reduced on a discrete lattice. However, for conjugated systems of interest, the discrete correction to the continuum limit are small. When the infinite onsite repulsion limit is relaxed the degenerate states split, forming a doublet of even and odd parity states. |
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