The fidelity and entanglement entropy in an
antiferromagnetic-ferromagnetic alternating Heisenberg chain are
investigated by using the method of density-matrix
renormalization-group. The effects of anisotropy on fidelity and
entanglement entropy are investigated. The relations between
fidelity, entanglement entropy and quantum phase transition are
analyzed. It is found that the quantum phase transition point can be
well characterized by both the ground-state entropy and fidelity for
large system.