中文摘要：

本文利用基于密度泛函理论框架下的广义梯度近似（GGA）方法,研究了过渡金属钼的晶体结构和弹性性质.零压下,计算所得的晶格常数（a=3.153）与实验值非常接近.与实验值比较,采用GGA＋U（U=1.5,2,2.5eV）的方法,计算得到的晶格常数a不如GGA的计算结果.此外,我们利用广义梯度近似（GGA）方法计算了钼的弹性性质,得到零压下钼的弹性常数分别为C11=449.7GPa,C12=169.7GPa,C44=96.2GPa,与实验值符合得很好.高压下钼的弹性常数计算值和Duffy等人用X衍射实验测量的实验值（0～24GPa）相符.体弹模量B0计算值（B0=263.05GPa）和实验值（B0=262.8GPa）非常接近.计算发现,随着压强的增大,体弹模量和剪切模量比值B/G一直保持大于1.75,说明钼在所研究的压强范围内一直保持较好的延展性.最后,还研究了体弹模量B,剪切模量G,杨氏模量E,泊松比σ,压缩波速VS,剪切波速VL,弹性各向异性因子A和克莱恩曼参数ζ与压强的变化关系.

英文摘要：

The structure and elastic properties of bcc Mo are investigated by using the generalized gradient approximation （GGA） in the framework of the density functional theory. At zero pressure, the calculated lattice parameter （ a = 3. 153 A） is in very good agreement with the available experimental data. Compared with the experimental values,the calculated results from the GGA＋U （U=1.5, 2, 2. 5 eV） method are not better than the results from the GGA method. In addition, we investigate the elastic properties of Mo using the GGA method. The calculated elastic constants Cn, Clz, and C44 at zero pressure are 449.7, 169.7, and 96.2 GPa, respectively, consistent well with experimental data. Our results under pressures are in good agreement with the energy-dispersive X-ray diffraction data by Dully et al （0 =24 GPa）. The calculated bulk modulus B0 （B0 = 263. 05 GPa） consists with the experimental value （B0 =262.8 GPa）. From the calculated results, we can find that the ratio of the bulk modulus and shear modulus has remained greater than 1. 75 with increasing pressure, indicating that the ductility of Mo keeps very well within the pressure range of our study. At last, the pressure dependence of the bulk modulus B（GPa）, shear modulus G, Young＇s modulus E, Poisson ratios a, shear sound velocities Vs, longitudinal sound velocities VL, elastic anisotropy factor Aand Kleinmann parameter are also investigated systematically.