https://doi.org/10.1007/s100510050053
Density-matrix renormalization study of the Hubbard model on a Bethe lattice
Laboratoire de Physique Quantique (UMR 5626 du CNRS) ,
IRSAMC, 118 route de Narbonne, 31062 Toulouse Cedex 4, France
Received:
8
February
1999
Revised:
14
June
1999
Published online: 15 February 2000
The half-filled Hubbard model on the Bethe lattice with coordination number
z=3 is studied using the density-matrix renormalization group (DMRG)
method. Ground-state properties such as the energy per site E, average
local magnetization 
, its fluctuations
and
various spin correlation functions
are determined as a function of the Coulomb interaction strength U/t.
The local magnetic moments 
increase monotonically with increasing Coulomb repulsion U/t
showing antiferromagnetic order between nearest neighbors
[
].
At large U/t, is strongly reduced
with respect to the saturation value 1/2 due to
exchange fluctuations between nearest neighbors (NN) spins
[
for 
].
shows a maximum for U/t=2.4-2.9 that results from the
interplay between the usual increase of 
with increasing U/t and the formation of important permanent moments
at large U/t. While NN sites show
antiferromagnetic spin correlations that increase with increasing
Coulomb repulsion, the next NN sites are very weakly correlated
over the whole range of U/t. The DMRG results are discussed and
compared with tight-binding calculations for U=0, independent DMRG studies
for the Heisenberg model and simple first-order perturbation estimates.
PACS: 71.10.Fd – Lattice fermion models (Hubbard model etc.) / 75.10.Lp – Band and itinerant models
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000
