TRIQS/CTHYB: A continuous-time quantum Monte Carlo hybridisation expansion solver for quantum impurity problems

Abstract

We present TRIQS/CTHYB, a state-of-the art open-source implementation of the continuoustime hybridisation expansion quantum impurity solver of the TRIQS package. This code is mainly designed to be used with the TRIQS library in order to solve the self-consistent quantum impurity problem in a multi-orbital dynamical mean field theory approach to strongly-correlated electrons, in particular in the context of realistic calculations. It is implemented in C++ for efficiency and is provided with a high-level Python interface. The code is ships with a new partitioning algorithm that divides the local Hilbert space without any user knowledge of the symmetries and quantum numbers of the Hamiltonian. Furthermore, we implement higher-order configuration moves and show that such moves are necessary to ensure ergodicity of the Monte Carlo in common Hamiltonians even without symmetry-breaking. PROGRAM SUMMARY

Simplified Parquet Equations for the Anderson Impurity Model: Comparison with Numerically Exact Solutions

“…We used the "selfenergy trick" to reduce NRG over-broadening effect [6]. The continuous-time hybridization-expansion (CT-HYB) quantum Monte Carlo calculations were performed using the solver included in TRIQS package [7]. Since this method works only at finite temperatures, we set k B T = 0.0125∆.…”

Realistic many-body approaches to materials with strong nonlocal correlations

“…The next two chapters deal with concrete applications using DFT+DMFT calculations based on the charge self-consistent combination of the mixed-basis pseudopotential method [74] for the DFT part and the CT-QMC method, as implemented in the TRIQS package [75,76], for the DMFT impurity problem.…”

Influence of oxygen vacancies on two-dimensional electron systems at SrTiO3-based interfaces and surfaces

“…We therefore advanced on the description of electronic correlations and applied the charge self-consistent merging of DFT with dynamical mean-field theory (DMFT) to the given surface defect problem [16]. Our approach [17] is here based on the combination of mixed-basis pseudopotential theory [18] for the DFT part and the continuous-time quantum Monte Carlo method [19,20], as implemented in the TRIQS package [21,22], for the DMFT impurity problem. In a slab supercell of 180 atomic sites, two structural oxygen-vacancy (OV) cases are investigated, namely a two-singlevacancies structure and a double-vacancy defect.…”