We calculate the zero-temperature q-dependent susceptibilities of the one-dimensional, S=1/2, transverse Ising model at the critical magnetic field and of the isotropic XY model in zero field which have not been previously determined. Our method, which is based on a rigorous method of calculating dynamic correlation functions for these models, provides precise numerical values for the susceptibilities at wave numbers q=kπ/M for integral M and odd integral k, as well as exact analytic results for the dominant singularities at q=0 and q=π.

• Received 23 October 1984

DOI:https://doi.org/10.1103/PhysRevB.31.637