Thermal transport in the anisotropic Heisenberg chain with S = 1/2 and   nearest-neighbor interactions
  The purpose of this note is to connect early work on thermal transport in spin-1/2 Heisenberg chains with uniaxial exchange anisotropy and nearest-neighbor interactions that was based on a moment analysis of the Fourier transform of the energy density correlation function with subsequent studies that make use of thermal current correlation functions. 
D. L. Huber