86,251 research outputs found

    Study of the ionic Peierls-Hubbard model using density matrix renormalization group methods

    Full text link
    Density matrix renormalization group methods are used to investigate the quantum phase diagram of a one-dimensional half-filled ionic Hubbard model with bond-charge attraction, which can be mapped from the Su-Schrieffer-Heeger-type electron-phonon coupling at the antiadiabatic limit. A bond order wave (dimerized) phase which separates the band insulator from the Mott insulator always exists as long as electron-phonon coupling is present. This is qualitatively different from that at the adiabatic limit. Our results indicate that electron-electron interaction, ionic potential and quantum phonon fluctuations combine in the formation of the bond-order wave phase

    Low-lying states in even Gd isotopes studied with five-dimensional collective Hamiltonian based on covariant density functional theory

    Full text link
    Five-dimensional collective Hamiltonian based on the covariant density functional theory has been applied to study the the low-lying states of even-even 148162^{148-162}Gd isotopes. The shape evolution from 148^{148}Gd to 162^{162}Gd is presented. The experimental energy spectra and intraband B(E2)B(E2) transition probabilities for the 148162^{148-162}Gd isotopes are reproduced by the present calculations. The relative B(E2)B(E2) ratios in present calculations are also compared with the available interacting boson model results and experimental data. It is found that the occupations of neutron 1i13/21i_{13/2} orbital result in the well-deformed prolate shape, and are essential for Gd isotopes.Comment: 11pages, 10figure

    Discussion on Event Horizon and Quantum Ergosphere of Evaporating Black Holes in a Tunnelling Framework

    Full text link
    In this paper, with the Parikh-Wilczek tunnelling framework the positions of the event horizon of the Vaidya black hole and the Vaidya-Bonner black hole are calculated respectively. We find that the event horizon and the apparent horizon of these two black holes correspond respectively to the two turning points of the Hawking radiation tunnelling barrier. That is, the quantum ergosphere coincides with the tunnelling barrier. Our calculation also implies that the Hawking radiation comes from the apparent horizon.Comment: 8 page