Strong-coupling solver for the quantum impurity model

Strong-coupling solver for the quantum impurity model

We propose a fast impurity solver for the general quantum impurity model based on the perturbation theory around the atomic limit, which can be used in combination with the local density approximation LDA and the dynamical mean-field theory DMFT . We benchmark the solver in the two-band Hubbard model within DMFT against quantum Monte Carlo QMC and numerical renormalization-group NRG results. We...

Diagrammatic Monte Carlo simulation of quantum impurity models – weak and strong coupling approach

Quantum solitons at strong coupling

We examine the effect of one loop quantum corrections on the formation of nontopological solitons in a strongly coupled scalar-fermionic Yukawa theory. The exact one fermion loop contribution is incorporated by using a nonlocal method to correct the local derivative expansion approximation (DE) of the effective action. As the Yukawa coupling is increased we find that the nonlocal corrections pl...

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

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 th...

Strong Coupling Perturbation Theory in Quantum Mechanics

We present a full introduction to the recent devised perturbation theory for strong coupling in quantum mechanics. In order to put the theory in a proper historical perspective, the approach devised in quantum field theory is rapidly presented, showing how it implies a kind of duality in perturbation theory, from the start. The approach of renormalization group in perturbation theory is then pr...