TRIQS/CTHYB: A Continuous-Time Quantum Monte Carlo Hybridization Expansion Solver for Quantum Impurity Problems

TL;DR

TRIQS/CTHYB is an efficient, open-source quantum impurity solver with advanced algorithms, designed for multi-orbital dynamical mean field theory, supporting realistic calculations with improved ergodicity.

Contribution

It introduces a new partitioning algorithm and higher-order configuration moves to enhance ergodicity and usability in quantum impurity problem solutions.

Findings

Efficient implementation in C++ with Python interface.

New partitioning algorithm that does not require symmetry knowledge.

Higher-order moves improve ergodicity in Monte Carlo simulations.

Abstract

We present TRIQS/CTHYB, a state-of-the art open-source implementation of the continuous-time 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.