Maximum entropy analytic continuation of anomalous self-energies

Maximum entropy analytic continuation of anomalous self-energies

Changming Yue and Philipp Werner
Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland

The anomalous self-energy plays an important role in the analysis of superconducting states. Its spectral weight provides information on the pairing glue of superconductors, but it can change in sign. In many numerical approaches, for example Monte Carlo methods based on the Nambu formalism, the anomalous self-energy is obtained on the Matsubara axis, and nonpositive spectral weight cannot be directly obtained using the standard maximum entropy analytic continuation method. Here, we introduce an auxiliary self-energy corresponding to a linear combination of the normal and anomalous self-energies. We analytically and numerically prove that this auxiliary function has non-negative spectral weight independent of the type of pairing symmetry, which allows us to compute the sign-changing spectrum of the original self-energy using the maximum entropy approach. As an application, we calculate the momentum-resolved spectral function of K3C60 in the superconducting state.

This data base provides plotting script, data and/or data for

all the figures of the above preprint. You can search it in 

Changming Yue's arXiv (submitted around the end of 03/2023) : 

https://arxiv.org/search/?query=Yue%2C+Changming&searchtype=author&abstracts=show&order=-submitted_date&size=50

The folder contains data and plotting script or code for 

(1) benchmark_Fig1 for Fig1

(2) benchmark_Fig2 for Fig2

(3) K3C60/Fig3 for Fig3

(4) K3C60/Fig4_FigS2 for Fig4

(5) K3C60/FigS1 for FigS1

(6) K3C60/Fig4_FigS2 for FigS2

Acknowledgements. — We thank S. Sakai for providing the ED data used in Fig. 3

and A.M.S Tremblay for helpful discussions. The calculations were performed on

the Beo05 cluster at the University of Fribourg. C.Y. and P.W. acknowledge

support from SNSF Grant No. 200021-196966.