3,633 research outputs found

    Density matrix renormalization group algorithms with a single center site

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    We develop a correction to the density matrix used in density matrix renormalization group calculations to take into account the incompleteness of the environment block. The correction allows successful calculations using only a single site in the center of the system, rather than the standard two sites, improving typical computation times by a factor of two to four. In addition, in many cases where ordinary DMRG can get stuck in metastable configurations, the correction eliminates the sticking. We test the new method on the Heisenberg S=1 chain.Comment: 4 pages, 4 figure

    Checkerboard patterns in the t-J model

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    Using the density matrix renormalization group, we study the possibility of real space checkerboard patterns arising as the ground states of the t-J model. We find that checkerboards with a commensurate (pi,pi) background are not low energy states and can only be stabilized with large external potentials. However, we find that striped states with charge density waves along the stripes can form approximate checkerboard patterns. These states can be stabilized with a very weak external field aligning and pinning the CDWs on different stripes.Comment: 4 pages, 5 figure

    Spin liquid phase of the S=12S=\frac{1}{2} J1βˆ’J2J_1-J_2 Heisenberg model on the triangular lattice

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    We study the S=1/2S=1/2 Heisenberg model on the triangular lattice with nearest neighbor interaction J1J_1 and next nearest neighbor interaction J2J_2 with the density matrix renormalization group. We are able to study long open cylinders with widths up to 9 lattice spacings. At an intermediate J2J_2 region 0.06≲J2/J1≲0.170.06 \lesssim J_2/J_1 \lesssim 0.17, we find evidence for a spin liquid (SL) state with short range spin-spin, bond-bond and chiral correlation lengths, bordered by a classical 120∘120^\circ N\'eel ordered state at small J2J_2 and by a two sub-lattice collinear magnetically ordered state at larger J2J_2. Focusing on J2/J1=0.1J_2/J_1 = 0.1, we find a number of signatures of a gapped SL phase: two quasi-degenerate ground states on even cylinders, with an energy gap that decreases exponentially with the cylinder width; a dimerization effect on odd cylinders; and large spin triplet and singlet bulk gaps.Comment: 5+4 pages, 4+7 figures, 1 table. v2 minor changes made for publication on PRB rapid communicatio
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