%0 Journal Article
%A Nghiem, H. T. M.
%A Costi, Theodoulos
%T Self-energy method for time-dependent spectral functions of the Anderson impurity model within the time-dependent numerical renormalization group approach
%J Physical review / B
%V 104
%N 20
%@ 1098-0121
%C Woodbury, NY
%I Inst.
%M FZJ-2021-04263
%P 205113
%D 2021
%X The self-energy method for quantum impurity models expresses the correlation part of the self-energy in terms of the ratio of two Green's functions and allows for a more accurate calculation of equilibrium spectral functions than is possible directly from the one-particle Green's function [Bulla et al., J. Phys.: Condens. Matter 10, 8365 (1998)], for example, within the numerical renormalization group method. In addition, the self-energy itself is a central quantity required in the dynamical mean field theory of strongly correlated lattice models. Here, we show how to generalize the self-energy method to the time-dependent situation for the prototype model of strong correlations, the Anderson impurity model. We use the equation-of-motion method to obtain closed expressions for the local Green's function in terms of a time-dependent correlation self-energy, with the latter being given as a ratio of a one-particle time-dependent Green's function and a higher-order correlation function. We benchmark this self-energy approach to time-dependent spectral functions against the direct approach within the time-dependent numerical renormalization group method. The self-energy approach improves the accuracy of time-dependent spectral function calculations, and the closed-form expressions for the Green's function allow for a clear picture of the time evolution of spectral features at the different characteristic time scales. The self-energy approach is of potential interest also for other quantum impurity solvers for real-time evolution, including time-dependent density matrix renormalization group and continuous-time quantum Monte Carlo techniques.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000719865400004
%R 10.1103/PhysRevB.104.205113
%U https://juser.fz-juelich.de/record/902441