# Thermal DMRG for highly frustrated quantum spin chains: a user perspective

## TL;DR

This paper evaluates the effectiveness of thermal DMRG in calculating magnetic properties of frustrated quantum spin chains at finite temperatures, highlighting its accuracy and limitations in different systems.

## Contribution

It demonstrates the applicability of thermal DMRG to frustrated spin chains and analyzes its temperature-dependent accuracy in these complex systems.

## Key findings

- Thermal DMRG accurately approximates magnetic observables in unfrustrated chains.
- In frustrated sawtooth chains, accuracy is limited to higher temperatures.
- Frustration affects the low-energy spectrum, impacting DMRG performance.

## Abstract

Thermal DMRG is investigated with emphasis of employability in molecular magnetism studies. To this end magnetic observables at finite temperature are evaluated for two one-dimensional quantum spin systems: a Heisenberg chain with nearest-neighbor antiferromagnetic interaction and a frustrated sawtooth (delta) chain. It is found that thermal DMRG indeed accurately approximates magnetic observables for the chain as well as for the sawtooth chain, but in the latter case only for sufficiently high temperatures. We speculate that the reason is due to the peculiar structure of the low-energy spectrum of the sawtooth chain induced by frustration.