We present a minimally entangled typical thermal state (METTS) quantum impurity solver for general multi-orbital systems at finite temperatures. We introduce an improved estimator for the single-particle Green's function that strongly reduces the large fluctuations at long imaginary time and low temperature, which were a severe limitation of the original algorithm. In combination with the fork tensor product states ansatz, we obtain a dynamical mean field theory (DMFT) quantum impurity solver, which we benchmark for single and three-band models down to low temperatures, including the effect of spin-orbit coupling in a realistic DMFT computation for the Hund's metal Sr2RuO4 down to low temperatures.
@article{arxiv.2312.13668,
title = {Finite Temperature Minimal Entangled Typical Thermal States Impurity Solver},
author = {Xiaodong Cao and E. Miles Stoudenmire and Olivier Parcollet},
journal= {arXiv preprint arXiv:2312.13668},
year = {2024}
}