Date of Original Version
Time-dependent spin autocorrelation functions and their spectral densities for the semi-infinite one-dimensionals=1/2 XY and XXZ models atT=∞ are determined in part by rigorous calculations in the fermion representation and in part by the recursion method in the spin representation. Boundary effects yield valuable new insight into the different dynamical processes which govern the transport of spin fluctuations in the two models. The results obtained for theXXX model bear the unmistakable signature of spin diffusion in the form of a squareroot infrared divergence in the spectral density.
Stolze, J., Viswanath, V. S., & Muller, G. (1992). Dynamics of semi-infinite quantum spin chains at T = ∞. Zeitschrift fur Physik B Condensed Matter, 82(1), 45-55.
Available at: http://dx.doi.org/10.1007/BF01320828