A Kondo impurity in one dimensional correlated conduction electrons

A spin-1/2 magnetic impurity coupled to a one-dimensional correlated electron system have been studied by applying the density renormalization group method. The Kondo temperature is substantially enhanced by strong repulsive interactions in the chain, but changes non-monotonically in the case of electron attraction. The magnetization of the impurity at zero- temperature shows local Fermi liquid behavior.Comment: 4 pages and 4 figures; ps-file

Improving the rejection sampling method in quasi-Monte Carlo methods

AbstractThe rejection sampling method is one of the most popular methods used in Monte Carlo methods. In this paper, we investigate and improve the performance of using a deterministic version of rejection method in quasi-Monte Carlo methods. It turns out that the “quality” of the point set generated by deterministic rejection method is closely related to the problem of quasi-Monte Carlo integration of characteristic functions, whose accuracy may be lost due to the discontinuity of the characteristic functions. We propose a method of smoothing characteristic functions in a rather general case. We replace the characteristic functions by continuous ones, without changing the value of the integrals. Using this smoothing technique, we modify the rejection method. An extended smoothed rejection method is described. Numerical experiments show that the extended smoothed rejection method is much more efficient than the standard quasi-Monte Carlo and the unsmoothed rejection method when used with low discrepancy sequences