Development of efficient approximation methods in dynamical mean field theory for multi-degree-of-freedom systems
Ryota Mizuno, Masayuki Ochi, Kazuhiko Kuroki
Although several impurity solvers in the dynamical mean field theory (DMFT) have been proposed, especially in multi-degree-of-freedom systems, there are practical difficulties arising from a trade-off between numerical costs and reliability. In this study, we re-interpret the iterative perturbation theory (IPT) from the perspective of the frequency dependence, and extend it such that costs and reliability can be compatible. From the same perspective, we also develop the methods in which the dual fermion calculation can be performed efficiently and can be combined with any impurity solver. We apply these methods to several models to evaluate their validity. We confirm that our methods show good agreements with the numerically exact continuous-time quantum Monte Carlo (CT-QMC) method in the local DMFT calculation, and can also capture important behaviors such as the pseudo gap in the DMFT + non-local calculation. In addition, the numerical costs are kept sufficiently small.
•Jan 12, 2021•0 citations