Density matrix numerical renormalization group for non-Abelian symmetries

TL;DR

This paper extends the density matrix NRG method to incorporate arbitrary non-Abelian symmetries, improving accuracy and efficiency in quantum impurity calculations such as the two-channel Kondo model under magnetic fields.

Contribution

The authors develop a generalized DM-NRG approach that preserves spectral sum rules and efficiently handles multiple non-Abelian symmetries in quantum impurity problems.

Findings

Enhanced accuracy in T-matrix calculations for the two-channel Kondo model.

Reduced computational time when using non-Abelian symmetries.

Demonstrated benefits over conventional NRG methods.

Abstract

We generalize the spectral sum rule preserving density matrix numerical renormalization group (DM-NRG) method in such a way that it can make use of an arbitrary number of not necessarily Abelian, local symmetries present in the quantum impurity system. We illustrate the benefits of using non-Abelian symmetries by the example of calculations for the T-matrix of the two-channel Kondo model in the presence of magnetic field, for which conventional NRG methods produce large errors and/or take a long run-time.