Abstract:  The structural and electronic properties of low-temperature orthorhombic PbZrO^₃(antiferroelectric phase) and higlrtemperature cubic phase(paraclectric) arc calculated using the first principle methods，which are
performed within the density functional theory using the projector augmented wave implemented in the Vienna ab initio Simulation Package, and the exchange-corrclation potential is treated in the local density approximation using
the Ceperly-Alder scheme.The first principles methods have been a powerful tool for obtaining accurate ground state and indicating the relevance betty ecn the microscopic structure and the properties，such as the ferroclectric
phase transition of BaTiO^₃，PbTiO3,.The ground state of PbZrO^₃ has been known to be antiferroclectric and the space groups of antiferroclectric and cubic phascare Pbam and Pm3m respectively.The initial structural parameters
arc adopted within previous studies.The structural relationship between cubic paraclectric and orthorhombic antiferroclectric phase can be understood with two distortions from the cubic geometry; one is the cooperative
distortion of the adjacent oxygen octahedra and the other is the opposite displacement of Pb ions between the adjacent unit cells, which dominates the antiferroclectric origin of the orthorhombic phase.This low-temperature
structure is characterized by antiparallcl displacement of Pb atoms in the a6 plane with subsequent rotation of ZrO^₆ octahedra, meanwhile, the positions of Zr atoms mainly remain unchanged.The lattice parameters and atomic
positions are relaxed until the total energy changed by less than 10^_一5 eV per conventional cell and residual force is smaller than 0. 0l eV/A. All the calculations reach good convergence.The calculated results show that the cubic and
orthorhombic phase are both direct gap insulators, and the band daps correspond to the values about 2. 61 and 2. 35 eV，respectively, In both cubic and orthorhombic PbZrO^₃，the valence band and the conduction band arc mainly
composed ofO2p, Zr 4d and Pb 6p states. Compared to the cubic phase, the main difference for the orthorhombic PbZrO^₃ is the enhanced peak around一5 eV, which consists mainly of O 2p and Pb 6^_s and 6^_P orbits.This behavior
reflects the increase of Pb一O bond hybridization, indicating the different ferroclectric behavior from structurally similar perovskites BaTiO^₃.Meanwhile, the results of the DOS show that the local Pb 6s states and O 2p states of
the orthorhombic phase shift to the lower energy, which reduce the total energy of the system, in favor of stabilizing the orthorhombic ground state of PbZrO^₃.Actually, our results of calculations indicate the energy of
antiferroclectric phase PbZrO^₃ is lower than that of cubic phase about 0.44 eV, In summary, the conclusion is that the additional hybridization of O2p and Pb 6s and 6p orbits in orthorhombic PbZrO^₃, could provide a deeper insight
for understanding the antiferroclectric propertics, as compared with the cubic phase.