We characterize multi-site quantum correlations in 1D finite-size XXZ chains at finite temperatures with global quantum discord. With the help of an exact diagonalization method and a thermal-tensor-network algorithm, the thermal-state discord G((rho) over cap (T)) is evaluated efficiently by well-developed optimization algorithms. Firstly, we find that in a finite temperature region, G((rho) over cap (T)) shows some footprint of the quantum phase transition of the model. The underlying mechanism is that (rho) over cap (T) captures the level crossing in the low-lying excited states. Secondly, ...
