Physics – Condensed Matter – Strongly Correlated Electrons
Scientific paper
2000-08-30
Int. J. Mod. Phys. B 14, 2529 (2000)
Physics
Condensed Matter
Strongly Correlated Electrons
20 pages RevTex, 3 figures
Scientific paper
10.1142/S0217979200002430
We reconsider the strong-coupling expansion for the Hubbard model recently introduced by Sarker and Pairault {\it et al.} By introducing slave particles that act as projection operators onto the empty, singly occupied and doubly occupied atomic states, the perturbation theory around the atomic limit distinguishes between processes that do conserve or do not conserve the total number of doubly occupied sites. This allows for a systematic $t/U$ expansion that does not break down at low temperature ($t$ being the intersite hopping amplitude and $U$ the local Coulomb repulsion). The fermionic field becomes a two-component field, which reflects the presence of the two Hubbard bands. The single-particle propagator is naturally expressed as a function of a $2 \times 2$ matrix self-energy. Furthermore, by introducing a time- and space-fluctuating spin-quantization axis in the functional integral, we can expand around a ``non-degenerate'' ground-state where each singly occupied site has a well defined spin direction (which may fluctuate in time). This formalism is used to derive the effective action of charge carriers in the lower Hubbard band to first order in $t/U$. We recover the action of the t-J model in the spin-hole coherent-state path integral. We also compare our results with those previously obtained by studying fluctuations around the large-$U$ Hartree-Fock saddle point.
Dupuis N.
Pairault Stephane
No associations
LandOfFree
A strong-coupling expansion for the Hubbard model does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A strong-coupling expansion for the Hubbard model, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A strong-coupling expansion for the Hubbard model will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-607683