Physical review. B, Condensed matter
Susceptibilities of one-dimensional quantum spin models at zero temperature
Gerhard H. Muller, Robert E. Shrock
Abstract
We calculate precise numerical values for the nondivergent direct or staggered zero-temperature susceptibilities of the one-dimensional, $S=\frac{1}{2}$, transverse Ising model at the critical field and for the isotropic $\mathrm{XY}$ model in zero field which have not been previously determined analytically. Our method is based on a rigorous approach to calculate dynamic correlation functions for these models. We also investigate the exact nature of the divergenices in the $q$-dependent susceptibilities. Our results are compared with existing predictions of approximate analytic approaches and numerical finite-chain calculations. Our result for the $\mathrm{XY}$ case is directly relevant for the interpretation of recent susceptibility measurements on the quasi-one-dimensional magnetic compound ${\mathrm{Cs}}_{2}$${\mathrm{CoCl}}_{4}$.