First-Principles Calculations on Phase Transition and Elastic Properties of CoN |

He De-Chun, Peng Yong, Li Su-Yuan and He Yong-Lin
College of Physics and Electrical Engineering, Hexi University, Zhangye 734000, China |

Received: December 7, 2015; In final form: May 10, 2016 |

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The structural phase transition and elastic properties of CoN are investigated by ab initio plane-wave pseudopotential density function theory method. The equilibrium lattice parameters a_{0}, elastic constants C_{ij}, bulk modulus B_{0} and its derivative B'_{0} are calculated. From the usual condition of equal enthalpy, the phase transition of CoN from zinc-blende to rocksalt structure occurs at 35.4 GPa with a volume collapse of about 15.6%, consistent with the calculated result 36 GPa (FP-LDA), but an uncertainty is about 4.4 GPa compared with the 31 GPa (ASA-GGA). All three independent elastic constants, C_{11}, C_{12}, and C_{44} for CoN are calculated from direct computation of stresses generated by small strains. Both C_{12} and C_{44} are less sensitive to pressure as compared with C_{11}. The calculated conclusions offer theoretical data for the further research of the mechanical properties for CoN. |

DOI: 10.12693/APhysPolA.130.743 PACS numbers: 62.20.-x, 62.20.de, 62.50.-p, 62.20.dq |