The numerical value for a universal quantity of a two-dimensional dimerized quantum antiferromagnet

The numerical value of a universal quantity associated with the quantum critical regime, namely $\chi_u c^2/T$, for a two-dimensional (2D) dimerized spin-1/2 antiferromagnet is calculated using the quantum Monte Carlo simulations (QMC). Here $\chi_u$, $c$, and $T$ are the uniform susceptibility, the spin-wave velocity, and the temperature, respectively. By simulating large lattices at moderately low temperatures, we find $\chi_u c^2/T \sim 0.32$. Our estimation of $\chi_u c^2/T$ deviates from the related analytic prediction but agrees with recent numerical calculations of other 2D dimerized spin-1/2 antiferromagnets.