498 research outputs found
Hubbard chain with a Kondo impurity
A Bethe Ansatz solution of a (modified) Hubbard chain with a Kondo impurity
of arbitrary spin S at a highly symmetric line of parameter space is proposed
and explored. Our results confirm the existence of a strong-coupling (line of)
fixed-point(s) with ferromagnetic Kondo coupling as first hypothetized by
Furusaki and Nagaosa on the basis of perturbative renormalization group
calculations. For on-site Hubbard repulsion and ferromagnetic Kondo exchange,
the ground state has spin S-1/2, i.e., is a singlet when S=1/2. The
contributions of the impurity to the magnetic susceptibility and
low-temperature specific heat are discussed. While the Wilson ratio is unity in
the half-filled band, it is found to be a function of density and interaction
away from half-filling.Comment: 5 pages, Revte
Comment on ``Solution of Classical Stochastic One-Dimensional Many-Body Systems''
In a recent Letter, Bares and Mobilia proposed the method to find solutions
of the stochastic evolution operator with a
non-trivial quartic term . They claim, ``Because of the conservation of
probability, an analog of the Wick theorem applies and all multipoint
correlation functions can be computed.'' Using the Wick theorem, they expressed
the density correlation functions as solutions of a closed set of
integro-differential equations.
In this Comment, however, we show that applicability of Wick theorem is
restricted to the case only.Comment: 1 page, revtex style, comment on paper Phys. Rev. Lett. {\bf 83},
5214 (1999
Solution of classical stochastic one dimensional many-body systems
We propose a simple method that allows, in one dimension, to solve exactly a
wide class of classical stochastic many-body systems far from equilibrium. For
the sake of illustration and without loss of generality, we focus on a model
that describes the asymmetric diffusion of hard core particles in the presence
of an external source and instantaneous annihilation. Starting from a Master
equation formulation of the problem we show that the density and multi-point
correlation functions obey a closed set of integro-differential equations which
in turn can be solved numerically and/or analyticallyComment: 2 figure
Exact multipoint and multitime correlation functions of a one-dimensional model of adsorption and evaporation of dimers
In this work, we provide a method which allows to compute exactly the
multipoint and multi-time correlation functions of a one-dimensional stochastic
model of dimer adsorption-evaporation with random (uncorrelated) initial
states.
In particular explicit expressions of the two-point
noninstantaneous/instantaneous correlation functions are obtained. The
long-time behavior of these expressions is discussed in details and in various
physical regimes.Comment: 6 pages, no figur
Relaxation kinetics of biological dimer adsorption models
We discuss the relaxation kinetics of a one-dimensional dimer adsorption
model as recently proposed for the binding of biological dimers like kinesin on
microtubules. The non-equilibrium dynamics shows several regimes: irreversible
adsorption on short time scales, an intermediate plateau followed by a
power-law regime and finally exponential relaxation towards equilibrium. In all
four regimes we give analytical solutions. The algebraic decay and the scaling
behaviour can be explained by mapping onto a simple reaction-diffusion model.
We show that there are several possibilities to define the autocorrelation
function and that they all asymptotically show exponential decay, however with
different time constants. Our findings remain valid if there is an attractive
interaction between bound dimers.Comment: REVTeX, 6 pages, 5 figures; to appear in Europhys. Letters; a Java
applet showing the simulation is accessible at
http://www.ph.tum.de/~avilfan/rela
Adiabatic connection between the RVB State and the ground state of the half filled periodic Anderson model
A one-parameter family of models that interpolates between the periodic
Anderson model with infinite repulsion at half-filling and a model whose ground
state is exactly the Resonating-Valence-Bond state is studied. It is shown
numerically that the excitation gap does not collapse. Therefore the ground
states of the two models are adiabatically connected.Comment: 6 pages, 3 figures Revte
A Model of Strongly Correlated Electrons with Condensed Resonating-Valence-Bond Ground States
We propose a new exactly solvable model of strongly correlated electrons. The
model is based on a - model of the CuO plane with infinitely large
repulsive interactions on Cu-sites, and it contains additional
correlated-hopping, pair-hopping and charge-charge interactions of electrons.
For even numbers of electrons less than or equal to 2/3-filling, we construct
the exact ground states of the model, all of which have the same energy and
each of which is the unique ground state for a fixed electron number. It is
shown that these ground states are the resonating-valence-bond states which are
also regarded as condensed states in which all electrons are in a single
two-electron state. We also show that the ground states exhibit off-diagonal
long-range order.Comment: 17 pages, 1 figure, v2: minor changes, v3: minor changes and typos
correction
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