钇在高压下的弹性性质和相稳定性研究

Study of Elasticity and Phase Stability of Yttrium under High Pressure

运用密度泛函平面波赝势方法(PWP)和广义梯度近似(GGA),对钇的3种结构相(体心立方bcc、面心立方fcc和六角密排堆积hcp)的总能和电子结构进行计算,得到了hcp结构的状态方程、价电子分布情况以及各种相在不同压力下的弹性常数和体模量,结果表明理论计算与实验值吻合得很好,比用局域密度近似(LDA)方法有了很大的改善.此外,还发现hcp相在加压到40GPa时发生相变,fcc是稳定的相.

Electronic structure and total energy of Yttrium's three phases are computed by means of plane wave pseudo-potential method(PWP) with generalized gradient approximation(GGA). We obtain the equation of state of hcp phase and elastic constants, bulk modulus of every phase, and these results are in good agreement with experiments' values. This method has much better improvement than other methods. We also obtain the electron populations of hcp structure and find the phase transition from hcp to fcc at pressure 40 GPa.