Recursion method in quantum spin dynamics: The art of terminating a continued fraction

Abstract
The results obtained from applications of the recursion method to quantum many-body dynamics can be greatly improved if an appropriate termination function is employed in the continued-fraction representation of the corresponding relaxation function. We present a general recipe for the construction and use of such termination functions along with two applications in spin dynamics. The method can be adapted to any other problem in quantum many-body dynamics.