Mats Granath, Hugo U. R. Strand
We develop a method for calculating the self energy of a quantum impurity
model coupled to a continuous bath, by stochastically generating a distribution
of finite Anderson models that are solved by exact diagonalization. Instead of
the fitting procedure used in the standard exact diago- nalization routines the
non-interacting local spectral function is used as a probability distribution
for the sampling. The method enables calculation of the full analytic
self-energy and single-particle Green's function in the complex frequency
plane, without analytic continuation, and can be used for both finite and zero
temperature at arbitrary fillings. Results are in very good agreement with
imaginary frequency data from continous-time quantum Monte Carlo calculations
for the single im- purity Anderson model as well as real frequency data from
dynamical mean field theory solutions of the paramagnetic Hubbard model using
numerical renormalization group. The method should be applicable to a wide
range of quantum impurity models and particularly useful when high precision
real frequency results are sought.
View original:
http://arxiv.org/abs/1201.6160
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