Algorithm for Linear Response Functions at Finite Temperatures: Application to ESR spectrum of s=1/2 Antiferromagnet Cu benzoate

TL;DR

This paper presents a new efficient numerical method for calculating finite-temperature linear response functions in quantum systems, demonstrated through ESR spectrum analysis of Cu benzoate.

Contribution

The paper introduces a novel combination of numerical techniques for stable finite-temperature response function calculations in strongly correlated quantum systems.

Findings

Method effectively computes response functions at finite temperatures.

Application successfully reproduces ESR spectrum of Cu benzoate.

Approach is broadly applicable to various quantum systems.

Abstract

We introduce an efficient and numerically stable method for calculating linear response functions $\chi(\vec{q},\omega)$ of quantum systems at finite temperatures. The method is a combination of numerical solution of the time-dependent Schroedinger equation, random vector representation of trace, and Chebyshev polynomial expansion of Boltzmann operator. This method should be very useful for a wide range of strongly correlated quantum systems at finite temperatures. We present an application to the ESR spectrum of s=1/2 antiferromagnet Cu benzoate.