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arXiv · 0803.3004

A Numerical Renormalization Group approach to Non-Equilibrium Green's Functions for Quantum Impurity Models

F. B. Anders
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Abstract

We present a method for the calculation of dynamical correlation functions of quantum impurity systems out of equilibrium using Wilson's numerical renormalization group. Our formulation is based on a complete basis set of the Wilson chain and embeds the recently derived algorithm for equilibrium spectral functions. Our method fulfills the spectral weight conserving sum-rule exactly by construction. A local Coulomb repulsion $U>0$ is switched on at $t=0$, and the asymptotic steady-state spectral functions are obtained for various values of $U$ as well as magnetic field strength $H$ and temperature $T$. These benchmark tests show excellent agreement between the time-evolved and the directly calculated equilibrium NRG spectra for finite $U$. This method could be used for calculating steady-state non-equilibrium spectral functions at finite bias through interacting nano-devices.

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F. B. Anders. 2008-03-20. A Numerical Renormalization Group approach to Non-Equilibrium Green's Functions for Quantum Impurity Models. https://doi.org/10.1088/0953-8984%2F20%2F19%2F195216

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