Scholarly Works, Center for Stochastic Processes in Science and Engineering (CSPISE)

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Browsing Scholarly Works, Center for Stochastic Processes in Science and Engineering (CSPISE) by Author "Chen, Y. C."

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    New phase in the one-dimensional t-J model
    Chen, Y. C.; Lee, T. K. (American Physical Society, 1993-05)
    A new phase of a gas of pairs of electrons bounded in a singlet state is found in the one-dimensional t -J model for J > 2t and the density of electrons less than 0.2. This phase was conjectured in the study of the diagonalization of small lattices [Phys. Rev. Lett. 66, 2388 (1991)]. The existence of this new phase for much larger lattice sizes is demonstrated by a combination of two numerical methods, the variational Monte Carlo and the power method. A trial wave function for this phase is proposed and shown to be in good agreement with the ground state obtained by the power method.
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    Spin-charge separation in the two-dimensional Hubbard and t-J models at low electronic density
    Chen, Y. C.; Moreo, A.; Ortolani, F.; Dagotto, E.; Lee, T. K. (American Physical Society, 1994-07)
    The spin- and density-correlation functions of the two-dimensional Hubbard model at low electronic density [n] are calculated in the ground state by using the power method, and at finite temperatures by using the quantum Monte Carlo technique. Both approaches produce similar results, which are in close agreement with numerical and high-temperature-expansion results for the two-dimensional t-J model. Using perturbative approximations, we show that the examination of the density-correlation function alone is not enough to support recent claims in the literature that suggested spin and charge separation in the low electronic density regime of the t-J model.
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    t-J model studied by the power Lanczos method
    Chen, Y. C.; Lee, T. K. (American Physical Society, 1995-03)
    The initial trial wave function used in a simple ground-state projection method, the power method, is systematically improved by using Lanczos algorithm. Much faster convergence to the ground state achieved by using these wave functions significantly reduces the effect of the fermion sign problem. The results for the ground state of the two-dimensional t-J model are presented. The density correlation function for the t-J model at small J shows a surprisingly good agreement with that of a system of noninteracting hard-core bosons.