]> BibSonomy publications for/author/Anfossi Physica A: Statistical Mechanics and its ApplicationsAug1247--256Parameterization of meandering phenomenon in a stable atmospheric boundary layer3682006Meandering parameterization 012008-04-22 10:36:30.0 Genova, ItalyAbstract Book of the XXIII IUPAP International Conference on Statistical Physics9-13 JulyEntanglement and Quantum Phase Transitions in Extended Hubbard Models2007correlated correlations entanglement extended fermions hubbard models multipartite phase quantum statphys23 strongly topic-8 transitions 2007-06-20 10:16:09.0The role of two-point and multipartite entanglement at Quantum Phase Transitions (QPTs) is investigated in fermionic systems, in which case the typical number of degrees of freedom involved at each site is larger than a qu-bit. We consider a bond-charge extended Hubbard model exactly solvable in one dimension which displays various QPTs. A comparative use of quantum mutual information and single-site Von Neumann entropy allows to distinguish at each transition the nature (if bipartite or multipartite) of the quantum correlations involved [1]. Their relative role is quantified through the Correlation Ratio, namely the ratio of quantum mutual information and single site entanglement. Moreover, the presence of an infinite range negativity is seen to signal a bipartite induced QPT. Whereas a finite value of infinite range quantum mutual information is able to capture the presence of off-diagonal long-range order induced by multipartite quantum correlations [2]. References\\ 1) A. Anfossi, P. Giorda, A. Montorsi, and F. Traversa, Two-Point Versus Multipartite Entanglement in Quantum Phase Transitions, Phys. Rev. Lett. 95, 056402 (2005)\\ 2) A. Anfossi, P. Giorda, and A. Montorsi, Entanglement in extended Hubbard models and Quantum Phase Transitions, Phys. Rev. B75 (2007) Genova, ItalyAbstract Book of the XXIII IUPAP International Conference on Statistical Physics9-13 JulyEntangelement and quantum phase diagram of the bond-charge extended Hubbard model2007dmrg entanglement extended hubbard luther-emery models phase quantum statphys23 topic-8 transitions 2007-06-20 10:16:09.0We 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). SBAC-PADconf/sbac-pad/2004142-149Parallel Implementation of a Lagrangian Stochastic Model for Pollution Dispersion.2004dblp 2006-05-26 00:00:00.0 International Journal of Parallel Programming5485-498Parallel Implementation of a Lagrangian Stochastic Model for Pollutant Dispersion.332005dblp 2006-05-26 00:00:00.0