Quantum Monte Carlo study of a spin-1/2 chain

An efficient finite-temperature quantum Monte Carlo simulation is described for nearest-neighbor spin-(1/2) models in the presence of external magnetic fields. The method is used to study the specific heat and susceptibility of ferromagnetic easy-plane cases with an in-plane magnetic field, and is applied to the one-dimensional magnet (${\mathrm{C}}_6$${\mathrm{H}}_{11}$${\mathrm{NH}}_3$)${\mathrm{CuBr}}_3$.