Dynamics of spin correlations in the spin-1/2 isotropic XY chain in a   transverse field
  Dynamic xx spin pair correlation functions for the isotropic spin-1/2 XY chain are calculated numerically for long open chains in the presence of a transverse magnetic field at finite temperature. As an application we discuss the temperature dependence of the spin-spin relaxation time in PrCl_3. 
O. Derzhko, T. Krokhmalskii and J. Stolze