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The DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.2013-05-23T01:43:15ZVariational approaches for electron-phonon interaction in strongly correlated systems
http://hdl.handle.net/2307/68
<Title>Variational approaches for electron-phonon interaction in strongly correlated systems</Title>
<Authors>Barone, Paolo</Authors>
<Issue Date>2006</Issue Date>
<Abstract>In this work we present two variational approaches to the electron-phonon interaction in
strongly correlated systems.
The first
approach that we discussed focuses mainly on the first aspect of the problem, whereas the
second one completed the picture including a faithful description of phonon properties. We
tested both in the paramagnetic sector of the Hubbard-Holstein model at T = 0, focusing on
ground-state properties of both electrons and phonons.</Abstract>2005-12-31T23:00:00ZGutzwiller scheme for electrons and phonons: The half-filled Hubbard-Holstein model
http://hdl.handle.net/2307/73
<Title>Gutzwiller scheme for electrons and phonons: The half-filled Hubbard-Holstein model</Title>
<Authors>Barone, Paolo; Raimondi, Roberto; Capone, Massimo; Castellani, Claudio; Fabrizio, Michele</Authors>
<Issue Date>2008-06-19T07:19:16Z</Issue Date>
<Is part of>Physical Review B</Is part of>
<Volume>77</Volume>
<Pages>235115</Pages>
<Abstract>We analyze the ground-state properties of strongly correlated electrons coupled with phonons by means of a generalized Gutzwiller wave function, which includes phononic degrees of freedom. We study in detail the paramagnetic half-filled Hubbard-Holstein model, where the electron-electron interaction can lead to a Mott transition and the electron-phonon coupling to a bipolaronic transition. We critically discuss the quality of the proposed wave function in describing the various transitions and crossovers that occur as a function of the parameters. Previous variational attempts are recovered as particular choices of the wave function, while keeping all the variational freedom allows to access regions of the phase diagram, otherwise inaccessible within previous variational approaches.</Abstract>2008-06-19T07:19:16ZExtended Gutzwiller wavefunction for the Hubbard-Holstein model
http://hdl.handle.net/2307/76
<Title>Extended Gutzwiller wavefunction for the Hubbard-Holstein model</Title>
<Authors>Barone, Paolo; Raimondi, Roberto; Capone, Massimo; Castellani, Claudio; Fabrizio, Michele</Authors>
<Issue Date>2007-07-20T08:20:21Z</Issue Date>
<Is part of>Europhysics Letters</Is part of>
<Volume>79</Volume>
<Pages>47003</Pages>
<Abstract>We introduce a new type of Gutzwiller variational wave function for correlated electrons coupled to phonons, able to treat on equal footing electronic and lattice degrees of freedom. We benchmark the wave function in the infinite-U Hubbard-Holstein model away from half-filling on a Bethe lattice, where we can directly compare with exact results by the Dynamical Mean-Field Theory. For this model, we find that variational results agree perfectly well with the exact ones. In particular the wave function correctly describes the crossover to a heavy polaron gas upon increasing the electron-phonon coupling.</Abstract>2007-07-20T08:20:21Z