arXiv:cond-mat/0104120 · Physical review. B, Condensed matter
Lineshapes of dynamical correlation functions in Heisenberg chains
Ralph Werner, Andreas Klümper
Abstract
We calculate lineshapes of correlation functions by use of complete diagonalization data of finite chains and analytical implications from conformal-field theory, density of states, and Bethe ansatz. The numerical data have different finite-size accuracy in the cases of the imaginary and real parts in the frequency and time representations of spin-correlation functions, respectively. The low-temperature, conformally invariant regime crosses over at ${T}^{*}\ensuremath{\approx}0.7J$ to a diffusive regime that in turn connects continuously to the high-temperature, interacting-fermion regime. The first-moment sum rule is determined.