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   COLLOQUIUM OF THE LABORATORY FOR COMPUTER DESIGN OF MATERIALS        
                   School of Computational Sciences	
                           (CSI 898-Sec 001) 
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Study of Stripe Phases and Superconductivity in an Electronic Model
                   for High Temperature Superconductors

                           Mariana Guerrero
             University of Maryland, College Park, MD

We study the two-dimensional Hubbard model, a purely  electronic model 
for high temperature superconductors, using two novel numerical methods 
(Quantum Monte Carlo and Density Matrix Renormalization Group). Results 
obtained  with these two methods agree well for small and intermediate 
values of the on-site Coulomb repulsion U. We calculate the ground-state 
energies and the spin and hole densities for a 12x3 lattice  with open 
boundary conditions and 6 holes doped away from half-filling. For U/t 
greater than 6 we find a ground-state with stripes, which consist of 
hole-rich walls separating antiferromagnetic domains. This result agrees 
with the experimental observation of stripe phases in the superconducting 
cuprates. We also revisit the problem of superconductivity in the 2-D 
Hubbard model.

                        Monday , September 11, 2000
                                  4:30 pm
                        Room 206, Science & Tech. I

Refreshments will be served.
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Find the schedule at http://csi.gmu.edu/lcdm/seminar/schedule.html