CAJ | 학술논문

利用投影缀加波方法对金属钒加压至400 GPa左右的结构相变过程进行了第一性原理研究. 计算了相变中的热力学转变压力和失稳转变压力, 并对相变前后的电子性质进行了研究. 结果表明: 钒在低压下为体心立方结构, 随着压力增大转变为菱方结构, 压力继续增大最后又重新转变为体心立方结构. 热力学计算得到的BCC→rh~u(α>109.47°)→rh~l(α<109.47°)→BCC三次转变压力分别为27,104和310 GPa. 利用剪切弹性常数C44计算得到的2次失稳压力分别为52和255 GPa. 能带计算表明, 在加压过程中高对称点Γ处靠近费米能级的能带由低压下的非电子占据态变为高压下的占据态, 而费米能级以上的电子态密度计算可见明显的s,p-d带间电子迁移现象.
이용투영철가파방법대금속범가압지400 GPa좌우적결구상변과정진행료제일성원리연구. 계산료상변중적열역학전변압력화실은전변압력, 병대상변전후적전자성질진행료연구. 결과표명: 범재저압하위체심립방결구, 수착압력증대전변위릉방결구, 압력계속증대최후우중신전변위체심립방결구. 열역학계산득도적BCC→rh~u(α>109.47°)→rh~l(α<109.47°)→BCC삼차전변압력분별위27,104화310 GPa. 이용전절탄성상수C44계산득도적2차실은압력분별위52화255 GPa. 능대계산표명, 재가압과정중고대칭점Γ처고근비미능급적능대유저압하적비전자점거태변위고압하적점거태, 이비미능급이상적전자태밀도계산가견명현적s,p-d대간전자천이현상.
Recent experiment revealed a new structural phase transition in vanadium at high pressure. Here the whole phase transition process under pressure up to 400 GPa was investigated from first principles calculation with projector augmented wave (PAW) method. The results show that body -centered cubic (BCC) vanadium firstly makes a transition to rhombohedral(rh) structure under pressure, and with increasing pressure, it transforms back to BCC again. Three thermodynamic phase transition pressures of BCC→rh~u(α > 109. 47°) →rh~1( α < 109. 47°) →BCC are 27, 104 and 310 GPa, respectively. Two instability pressures obtained by calculation of shear elastic constant C_(44) at different pressures are 52 and 255 GPa. Electronic properties calculation reveals that bands near Γ point gradually move below the Fermi level and become occupied condition. Calculation of decomposed density of states at Fermi level presents obvious s, p-d electrons transition among bands.