2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/28135Effects of randomness on the spin-1/2 and 1 antiferromagnetic Heisenberg chains are studied using the quantum Monte Carlo method with the continuous-time loop algorithm. We precisely calculated the uniform susceptibility, string order parameter, spatial and temporal correlation length, and the dynamical exponent, and obtained a phase diagram. The generalization of the continuous-time loop algorithm for the systems with higher-S spins is also presented.5 pages, 2 EPS figures; to be published in "Computer Simulation Studies in Condensed Matter Physics XI," Eds. D. P. Landau and H.-B. Schuettler (Springer Verlag, Heidelberg, Berlin, 1998)Disordered Systems and Neural NetworksStatistical Mechanicstext