scholarly journals Striped phases in the two-dimensional Hubbard model with long-range Coulomb interaction

1998 ◽  
Vol 58 (20) ◽  
pp. 13506-13509 ◽  
Author(s):  
G. Seibold ◽  
C. Castellani ◽  
C. Di Castro ◽  
M. Grilli
Keyword(s):  
Hubbard Model ◽  
Long Range ◽  
Coulomb Interaction ◽  
Two Dimensional ◽  
Striped Phases

PHASE SEPARATION IN THE TWO-DIMENSIONAL HUBBARD MODEL

2005 ◽  
Vol 19 (01n03) ◽  
pp. 299-302 ◽  
Author(s):  
M. YU ◽  
H. Q. LIN
Keyword(s):  
Phase Separation ◽  
Hubbard Model ◽  
Coulomb Interaction ◽  
Single Band ◽  
Study Phase ◽  
Two Dimensional ◽  
Stripe Phase ◽  
Hartree Fock ◽  
Band Filling

In this paper, we study phase separation in the two-dimensional single-band Hubbard model with the unrestricted Hartree-Fock(UHF) method and the restricted Hartree-Fock (RHF) method. We perform the calculation for square lattices and rectangle lattices. It is observed that the stripe phase exists and it depends on three aspects: geometry of the lattice, Coulomb interaction U and band filling n. To gain more physical insights, we consider the Hubbard model with spin dependent hoppings: t↑ and t↓, and study the effect of varying [Formula: see text] on the phase separation.

CORRELATION EFFECTS IN SOLID C60

1992 ◽  
Vol 06 (23n24) ◽  
pp. 3915-3921 ◽  
Author(s):  
R.W. Lof ◽  
M.A. van Veenendaal ◽  
B. Koopmans ◽  
A. Heessels ◽  
H.T. Jonkman ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hubbard Model ◽  
Long Range ◽  
Coulomb Interaction ◽  
Auger Spectrum ◽  
Correlation Effects ◽  
Highly Correlated ◽  
Molecular Excitons ◽  
Bucky Ball

The bandgap of solid C 60 is found to be 2.3±0.1 eV . The on-site molecular C 60 Coulomb interaction (U) as determined from the KVV C 60 Auger spectrum is found to be 1.6 ±.2 eV . This value of U is shown to be consistent with Frenkel type molecular excitons in the 1.5–2 eV range. These results lead us to suggest that doped C 60 should be considered as a highly correlated system with U/W comparable to that in high T c cuprates. The Auger spectroscpoy results are consistent with a rather long range Coulomb interaction on a single bucky ball indicating that a Hubbard model is not suitable to describe the electronic structure of a C 60 molecule.

REMARK ON THE EXISTENCE OF LONG-RANGE ORDER IN QUASI-TWO-DIMENSIONAL HUBBARD MODEL

1996 ◽  
Vol 10 (08) ◽  
pp. 341-346 ◽  
Author(s):  
A. BELKASRI ◽  
J.L. RICHARD
Keyword(s):  
Thin Film ◽  
High Temperature ◽  
Theoretical Analysis ◽  
Hubbard Model ◽  
Long Range ◽  
High Temperature Superconductivity ◽  
Type Model ◽  
Long Range Order ◽  
Two Dimensional ◽  
2D System

Recently in many works on the mechanism of high temperature superconductivity (see for example Refs. 1–6), quasi-averages like <ck↑c−k↓> were considered even in the case of a dimension less or equal two. But it is well known from the old work of Hohenberg7 that these quasi-averages are zero at T≠0 in case of 1 and 2 dimensions. In this communication we generalize the Hohenberg’s result to any kind of Hubbard type model on lattice and prove that in the case of quasi-two-dimension, the theorem of Hohenberg is not in contradiction with having <ck↑c−k↓>≠0 (at T≠0). In practice this makes sense to compare the data for a thin film (which can be considered as quasi-2D system) to the theoretical analysis based on quasi-two-dimensional models, but not for strictly two-dimensional case.

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