3,633 research outputs found

### Density matrix renormalization group algorithms with a single center site

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

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 $S=\frac{1}{2}$ $J_1-J_2$ Heisenberg model on the triangular lattice

We study the $S=1/2$ Heisenberg model on the triangular lattice with nearest
neighbor interaction $J_1$ and next nearest neighbor interaction $J_2$ with the
density matrix renormalization group. We are able to study long open cylinders
with widths up to 9 lattice spacings. At an intermediate $J_2$ region $0.06
\lesssim J_2/J_1 \lesssim 0.17$, we find evidence for a spin liquid (SL) state
with short range spin-spin, bond-bond and chiral correlation lengths, bordered
by a classical $120^\circ$ N\'eel ordered state at small $J_2$ and by a two
sub-lattice collinear magnetically ordered state at larger $J_2$. Focusing on
$J_2/J_1 = 0.1$, 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
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