Direct Calculation of Dynamical Susceptibility in Strongly Fluctuating Quantum Spin Systems

Abstract

We propose a direct numerical method to calculate the dynamicalsusceptibility, χ''(ω), in strongly fluctuating quantum systems, where the system is nonmagnetic but the exchange effect is very strong.We demonstrate this method by calculating ESR line shape χ''(ω) of the one dimensional antiferromagnetic Heisenberg model (S=1/2) andcomparing the results with those obtained by other methods and experiments.