Quantum and Classical Thermal Correlations in Spin-1 Heisenberg Chain with Alternating Single-Ion Anisotropy

In the present paper, we study the quantum phase transition in a spin-1 Heisenberg model with two and three particles by using pairwise classical and quantum thermal correlations and entanglement measures, that is, the generalized concurrence and the negativity at finite temperatures. We have used thermodynamic functions of particle number and particle susceptibility to characterize the thermodynamical behavior. The pairwise correlations are derived based on a necessary and sufficient condition for the zero-discord state. We obtain analytical results for the coherence-vector representation of a bipartite state. Using the exact diagonalization technique, we demonstrate that the quantum critical points, detected by the particle number and the particle susceptibility, are ultimately in close correspondence to that of thermal pairwise correlations and entanglement measures.