Investigation of the Quantum Correlations for a S=1/2 Ising- Heisenberg   Model on a Symmetrical Diamond Chain
  We consider the quantum correlations for a S=1/2 Ising- Heisenberg model of a symmetrical diamond chain. Firstly, we compare concurrence, quantum discord and 1- norm geometric quantum discord of an ideal diamond chain in the absence of magnetic field. The results show no simple ordering relations between these quantum correlations, so that quantum discord may be smaller or larger than the 1-norm geometric quantum discord, which this observation contradict the previous result that provided by F. M. Paula [1]. Symmetrical behavior of quantum correlation versus ferromagnetic and anti- ferromagnetic coupling constant J is considerable. The effect of external magnetic field H and temperature- dependence is also considered. Furthermore, we study quantum discord and geometric measure of quantum discord with the effect of next nearest neighbor interaction between nodal Ising sites for a generalized diamond chain, and we observe coexistence of phases with different values of magnetic field for quantum correlations. Moreover, entanglement sudden death occurs while quantum discord, 1- norm geometric quantum discord and geometric quantum discord are immune from sudden death. 
E. Faizi, H. Eftekhari
quant-ph