76,761 research outputs found
Comment on "Time-Dependent Density-Matrix Renormalization Group: A Systematic Method for the Study of Quantum Many-Body Out-of- Equilibrium Systems"
In a recent Letter [Phys. Rev. Lett. 88, 256403(2002), cond-mat/0109158]
Cazalilla and Marston proposed a time-dependent density- matrix renormalization
group (TdDMRG) algorithm for the accurate evaluation of out-of-equilibrium
properties of quantum many-body systems. For a point contact junction between
two Luttinger liquids, a current oscillation develops after initial transient
in the insulating regime. Here we would like to point out that (a) the observed
oscillation is an artifact of the method; (b) the TdDMRG can be significantly
improved by incorporating the non-equilibrium evolution of the goundstate into
the density matrix.Comment: 1 page, 2 figure
Critical behavior of the S=3/2 antiferromagnetic Heisenberg chain
Using the density-matrix renormalization-group technique we study the
long-wavelength properties of the spin S=3/2 nearest-neighbor Heisenberg chain.
We obtain an accurate value for the spin velocity v=3.8+- 0.02, in agreement
with experiment. Our results show conclusively that the model belongs to the
same universality class as the S=1/2 Heisenberg chain, with a conformal central
charge c=1 and critical exponent eta=1Comment: RevTeX (version 3.0), 4 twocolumn pages with 4 embedded figure
Superconductivity and Phase Diagram in (LiFe)OHFeSeS
A series of (LiFe)OHFeSeS (0 x 1)
samples were successfully synthesized via hydrothermal reaction method and the
phase diagram is established. Magnetic susceptibility suggests that an
antiferromagnetism arising from (LiFe)OH layers coexists with
superconductivity, and the antiferromagnetic transition temperature nearly
remains constant for various S doping levels. In addition, the lattice
parameters of the both a and c axes decrease and the superconducting transition
temperature T is gradually suppressed with the substitution of S for Se,
and eventually superconductivity vanishes at = 0.90. The decrease of T
could be attributed to the effect of chemical pressure induced by the smaller
ionic size of S relative to that of Se, being consistent with the effect of
hydrostatic pressure on (LiFe)OHFeSe. But the detailed
investigation on the relationships between and the crystallographic
facts suggests a very different dependence of on anion height from
the Fe2 layer or -Fe2- angle from those in FeAs-based superconductors.Comment: 6 pages, 6 figure
- β¦