CAJ | 학술논문

运用基于赝势平面波基组的密度泛函程序VASP并结合Quantum ESPRESSO，Phonopy软件包对压力下VN的结构、力学性质、声子色散关系进行了第一性原理的研究．分别对NaCl型（B1），CsCl型（B2）， WC型（ Bh）三种构型的VN进行了计算，三种结构的体积能量曲线、焓压关系和声子谱表明在常压下六角WC结构与立方结构相比更稳定．随着压力增加VN由Bh结构到B1结构的相变发生在30 GPa左右，而B1结构到B2结构的相变可能发生在150 GPa左右．常压下三种结构的VN是力学稳定的，其弹性常数和弹性模量都有随压强的增大而增加的趋势，三者都是脆性材料．B1结构和B2结构坐标基矢方向上的杨氏模量数值与体对角线方向上的差距较大，体现出明显的各向异性．随压力的增加B1结构各向异性程度增大而B2结构各向异性程度减小．
운용기우안세평면파기조적밀도범함정서VASP병결합Quantum ESPRESSO，Phonopy연건포대압력하VN적결구、역학성질、성자색산관계진행료제일성원리적연구．분별대NaCl형（B1），CsCl형（B2）， WC형（ Bh）삼충구형적VN진행료계산，삼충결구적체적능량곡선、함압관계화성자보표명재상압하륙각WC결구여립방결구상비경은정．수착압력증가VN유Bh결구도B1결구적상변발생재30 GPa좌우，이B1결구도B2결구적상변가능발생재150 GPa좌우．상압하삼충결구적VN시역학은정적，기탄성상수화탄성모량도유수압강적증대이증가적추세，삼자도시취성재료．B1결구화B2결구좌표기시방향상적양씨모량수치여체대각선방향상적차거교대，체현출명현적각향이성．수압력적증가B1결구각향이성정도증대이B2결구각향이성정도감소．
The structure, elastic properties and phonon dispersion relation of VN under high pressure are studied by using density functional program VASP, Quantum ESPRESSO and Phonopy package.Three configurations of NaCl (B1), CsCl (B2) and WC (Bh) phases of VN are investigated, respectively.The volume energy curve, enthalpy-pressure relation and phonon spectrum show that the hexagonal WC structure is more stable compared with the cubic structures at atmospheric pressure.With the increase in pressure we find that the phase transition of VN from Bh structure to B1 structure may occur at about 30 GPa and that from B1 structure to B2 structure at about 150 GPa.The three kinds of VN are mechanical stable at ambient pressure, the elastic constants and elas-tic moduli increase with the increasing pressure.Three kinds of VN are brittle materials.The Young′s modulus values on the B1 and B2 structure coordinates structural basis vector directions differ significantly from those on the body diagonal direction and show obvious anisotropy.The anisotropy of B1 structure increases, while that of B2 structure decreases with the increase in pressure.