%0 Book Section %1 statphys23_0038 %A Anfossi, A. %A Montorsi, A. %A Boschi, C. Degli Esposti %B Abstract Book of the XXIII IUPAP International Conference on Statistical Physics %C Genova, Italy %D 2007 %E Pietronero, Luciano %E Loreto, Vittorio %E Zapperi, Stefano %K dmrg entanglement extended hubbard luther-emery models phase quantum statphys23 topic-8 transitions %T Entangelement and quantum phase diagram of the bond-charge extended Hubbard model %U http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=38 %X We determine the quantum phase diagram of the one-dimensional Hubbard model with bond-charge interaction $X$ (Hirsch model) in addition to the usual Coulomb repulsion $U$ at half-filling and $T=0$ 1-2. Such an extension is quite natural since the charge in the bond affects both screening and the effective potential acting on valence electrons; therefore the Wannier orbitals and the hopping between them should vary with the charge. The Hirsch model had been studied, in two dimensions, in the context of hole superconductivity 3, while a modified version of it has been derived as an effective model for the cuprates and shows enhanced $d$-wave superconducting correlations 4. Moreover, recently it has been paramount to broader audiences and its relevance has been discussed in the context of mesoscopic transport 5 and quantum information 6 in one dimensional systems. By means of the density-matrix renormalization group algorithm the charge gap closure is examined by both standard finite-size scaling analysis and looking at singularities in the derivatives of single-site entanglement. The results of the two techniques show that a quantum phase transition takes place (at a finite Coulomb interaction $u_c(x)$ for $x0.5$). The novel Luther-Emery phase is characterized by dominant incommensurate singlet-superconducting correlations at large distances, the incommensurability showing up in the spin and density structure factors. Furthermore, we find that inside the insulating phase there is a spin transition, separating the expected spin-density wave phase from a spontaneously dimerized bond-ordered wave one (fully gapped phase), the quantum phase transition being of Kosterlitz-Thouless type. References:\\ 1) A. Anfossi, C. Degli Esposti Boschi, A. Montorsi, and F. Ortolani, Phys. Rev. B 73, 085113 (2006).\\ 2) A. Anfossi, C. Degli Esposti Boschi, A. Montorsi, F. Ortolani, A. A. Aligia, L. Arrachea, A. O. Dobry, C. Gazza, M. E. Torio, Incommensurability and unconventional superconductor to insulator transition in the Hubbard model with bond-charge interaction, preprint march 2007\\ 3) J. E. Hirsch, Physica C 158, 326 (1989); J. E. Hirsch and F. Marsiglio, Phys. Rev. B 39, 11515 (1989).\\ 4) L. Arrachea and A. A. Aligia, Phys. Rev. B 59, 1333 (1999); ibid 61, 9686 (2000).\\ 5) A. Hubsch et al, Phys. Rev. Lett. 96, 196401 (2006).\\ 6) A. Anfossi, P. Giorda, A. Montorsi, and F. Traversa, Phys. Rev. Lett. 95, 056402 (2005); A. Anfossi, P. Giorda, and A. Montorsi, Phys. Rev. B 75, in production (2007).

@incollection{statphys23_0038, abstract = {We determine the quantum phase diagram of the one-dimensional Hubbard model with bond-charge interaction $X$ (Hirsch model) in addition to the usual Coulomb repulsion $U$ at half-filling and $T=0$ [1-2]. Such an extension is quite natural since the charge in the bond affects both screening and the effective potential acting on valence electrons; therefore the Wannier orbitals and the hopping between them should vary with the charge. The Hirsch model had been studied, in two dimensions, in the context of hole superconductivity [3], while a modified version of it has been derived as an effective model for the cuprates and shows enhanced $d$-wave superconducting correlations [4]. Moreover, recently it has been paramount to broader audiences and its relevance has been discussed in the context of mesoscopic transport [5] and quantum information [6] in one dimensional systems. By means of the density-matrix renormalization group algorithm the charge gap closure is examined by both standard finite-size scaling analysis and looking at singularities in the derivatives of single-site entanglement. The results of the two techniques show that a quantum phase transition takes place (at a finite Coulomb interaction $u_{c}(x)$ for $x\ge 0.5$). The novel Luther-Emery phase is characterized by dominant incommensurate singlet-superconducting correlations at large distances, the incommensurability showing up in the spin and density structure factors. Furthermore, we find that inside the insulating phase there is a spin transition, separating the expected spin-density wave phase from a spontaneously dimerized bond-ordered wave one (fully gapped phase), the quantum phase transition being of Kosterlitz-Thouless type. References:\\ 1) A. Anfossi, C. Degli Esposti Boschi, A. Montorsi, and F. Ortolani, Phys. Rev. B 73, 085113 (2006).\\ 2) A. Anfossi, C. Degli Esposti Boschi, A. Montorsi, F. Ortolani, A. A. Aligia, L. Arrachea, A. O. Dobry, C. Gazza, M. E. Torio, \textit{Incommensurability and unconventional superconductor to insulator transition in the Hubbard model with bond-charge interaction}, preprint march 2007\\ 3) J. E. Hirsch, Physica C 158, 326 (1989); J. E. Hirsch and F. Marsiglio, Phys. Rev. B 39, 11515 (1989).\\ 4) L. Arrachea and A. A. Aligia, Phys. Rev. B 59, 1333 (1999); ibid 61, 9686 (2000).\\ 5) A. Hubsch \emph{et al}, Phys. Rev. Lett. 96, 196401 (2006).\\ 6) A. Anfossi, P. Giorda, A. Montorsi, and F. Traversa, Phys. Rev. Lett. 95, 056402 (2005); A. Anfossi, P. Giorda, and A. Montorsi, Phys. Rev. B 75, in production (2007).}, added-at = {2007-06-20T10:16:09.000+0200}, address = {Genova, Italy}, author = {Anfossi, A. and Montorsi, A. and Boschi, C. Degli Esposti}, biburl = {https://www.bibsonomy.org/bibtex/2860a3c355465487790034ca6a0f8256c/statphys23}, booktitle = {Abstract Book of the XXIII IUPAP International Conference on Statistical Physics}, editor = {Pietronero, Luciano and Loreto, Vittorio and Zapperi, Stefano}, interhash = {f5b0854c9f658fafb243b1d7098c791f}, intrahash = {860a3c355465487790034ca6a0f8256c}, keywords = {dmrg entanglement extended hubbard luther-emery models phase quantum statphys23 topic-8 transitions}, month = {9-13 July}, timestamp = {2007-06-20T10:16:10.000+0200}, title = {Entangelement and quantum phase diagram of the bond-charge extended Hubbard model}, url = {http://st23.statphys23.org/webservices/abstract/preview_pop.php?ID_PAPER=38}, year = 2007 }