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基于密度泛函理论(DFT)的平面波赝势方法对密排六方结构(hcp)铍(α-Be)的弹性性能进行了第一性原理计算研究。利用Material Studio软件的CASTEP模块并采用广义梯度近似(GGA)完成计算。分别得到了铍单晶体的弹性常数,铍多晶体的体积模量、剪切模量、杨氏模量、泊松比等参数对外加静水压变化(0~100 GPa)和对环境温度(0~1300 K)变化的变化规律。还利用第一性原理数值模拟方法对体心立方结构(bcc)的铍(β-Be)的弹性性能进行了计算。计算结果与文献实验数据符合度高。结果显示:各弹性参数值随压力的增长而单调增加,升温过程的影响作用则相反;描述铍晶体变形耦合性的C_(12)和C_(13)对压力或温度变化比其他弹性参数更为敏感;加压过程使铍晶格结构参数c/a值增加并趋向理想密排值,而在温升过程中这个值则持续降低;加压过程是一个原子密堆度提高的过程,据此对铍高压hcp-fcc(面心立方结构)相变的可能性和实现形式进行了讨论。
The elastic properties of hexagonal close-packed hexagonal structure (hcp) beryllium (α-Be) are studied by the first-principles calculations based on the density functional theory (DFT) plane wave pseudopotential method. Take advantage of the CASTEP module in Material Studio software and perform calculations using Generalized Gradient Approximation (GGA). The elastic constants of beryllium single crystal, volume modulus, shear modulus, Young’s modulus and Poisson’s ratio of beryllium polycrystal were obtained respectively. The change of external hydrostatic pressure (0-100 GPa) and ambient temperature (0 ~ 1300 K) changes in the law of change. The first-principle numerical simulation method was also used to calculate the elastic properties of bcc beryllium (β-Be). The calculated results are in good agreement with the experimental data in the literature. The results show that the elastic parameters increase monotonously with the increase of pressure, and the influence of heating process is opposite. The change of pressure or temperature of C_ (12) and C_ (13), which describe the deformation coupling of beryllium, is more than other elastic parameters Sensitive; pressure process makes beryllium lattice parameter c / a value increases and tends to the ideal density value, and in the process of temperature rise this value continues to decrease; pressure process is a process of increasing the atomic density, according to which The possibility and realization of phase transformation of beryllium high pressure hcp-fcc (face-centered cubic structure) are discussed.