title: Gutzwiller wave function for finite systems: superconductivity in the Hubbard model.
abstract: We study the superconducting phase of the Hubbard model using the Gutzwiller variational wave function (GWF) and the recently proposed diagrammatic expansion technique (DE-GWF). The DE-GWF method works on the level of the full GWF and in the thermodynamic limit. Here, we consider a finite-size system to study the accuracy of the results as a function of the system size (which is practically unrestricted). We show that the finite-size scaling used, e.g. in the variational Monte Carlo method can lead to significant, uncontrolled errors. The presented research is the first step towards applying the DE-GWF method in studies of inhomogeneous situations, including systems with impurities, defects, inhomogeneous phases, or disorder.
authors.affiliation: Marian Smoluchowski Institute of Physics, Jagiellonian University, ulica Łojasiewicza 11, PL-30-348 Kraków, Poland. Faculty of Mathematics and Computer Science, Jagiellonian University, ulica Łojasiewicza 6, PL-30-348 Kraków, Poland.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Tomski
authors.forename: Jan
authors.initials: J
authors.lastname: Kaczmarczyk