Metal-insulator transition and strong-coupling spin liquid in the t−t′t{-}t^\prime Hubbard model

We study the phase diagram of the frustrated $t{-}t^\prime$ Hubbard model on the square lattice by using a novel variational wave function. Taking the clue from the backflow correlations that have been introduced long-time ago by Feynman and Cohen and have been used for describing various interacting systems on the continuum (like liquid $^3$He, the electron jellium, and metallic Hydrogen), we consider many-body correlations to construct a suitable approximation for the ground state of this correlated model on the lattice. In this way, a very accurate {\it ansatz} can be achieved both at weak and strong coupling. We present the evidence that an insulating and non-magnetic phase can be stabilized at strong coupling and sufficiently large frustrating ratio $t^\prime/t$.Comment: 8 pages, Proceedings of the HFM2008 Conferenc

Metal-insulator transition and strong-coupling spin liquid in the t−t′t{-}t^\prime Hubbard model

We study the phase diagram of the frustrated $t{-}t^\prime$ Hubbard model on the square lattice by using a novel variational wave function. Taking the clue from the backflow correlations that have been introduced long-time ago by Feynman and Cohen and have been used for describing various interacting systems on the continuum (like liquid $^3$He, the electron jellium, and metallic Hydrogen), we consider many-body correlations to construct a suitable approximation for the ground state of this correlated model on the lattice. In this way, a very accurate {\it ansatz} can be achieved both at weak and strong coupling. We present the evidence that an insulating and non-magnetic phase can be stabilized at strong coupling and sufficiently large frustrating ratio $t^\prime/t$.Comment: 8 pages, Proceedings of the HFM2008 Conferenc

Relazione sull'intervento di controllo e manutenzione della Rete Sismica Digitale dell'Osservatorio Vesuviano all'Etna

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Unidirectional d-wave superconducting domains in the two-dimensional t-J model

Motivated by the recently observed pattern of unidirectional domains in high-T_c superconductors [Y. Kohsaka et al., Science 315, 1380 (2007)], we investigate the emergence of spontaneous modulations in the d-wave superconducting resonating valence bond phase using the t-J model at x=1/8 doping. Half-filled charge domains separated by four lattice spacings are found to form along one of the crystal axis leading to modulated superconductivity with out-of-phase d-wave order parameters in neighboring domains. Both renormalized mean-field theory and variational Monte Carlo calculations yield that the energies of modulated and uniform phases are very close to each other.Comment: 4 pages, 5 figures, minor revisions, and added reference

Rete Sismica Mt.Etna: relazione sull'intervento di installazione della Rete Permanente

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Relazione sull'intervento di installazione di una Rete Sismica Digitale all'Etna nell'ambito del Programma di Coordinamento GNV

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Rete Sismica Mt.Etna: relazione sul completamento della Rete Permanente orientale e sull'installazione della Rete Mobile Digitale

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Relazione sull'intervento di controllo della Rete Sismica dell'Osservatorio Vesuviano all'Etna

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