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首页> 外文期刊>Physical review >Phase stability, elasticity, and theoretical strength of polonium from first principles
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Phase stability, elasticity, and theoretical strength of polonium from first principles

机译：从第一原理看stability的相稳定性，弹性和理论强度

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Employing full-potential linearized augmented plane-wave method, we investigate the stability of Po in its ground-state simple cubic structure (α-Po) with respect to the trigonal spiral structure exhibited by Se and Te and to the displacive phase transformations into either tetragonal or trigonal phases. The origin of the phase stability of a-Po is analyzed with the help of densities of states, electronic band structures, and total energies of competing higher-energy structures corresponding to selected stationary points of the total energy. The electronic structures "and total energies are calculated both within the generalized gradient approximation and local-density approximation (LDA) to the exchange-correlation energy as well as with and without inclusion of the spin-orbit (SO) coupling. The total energies are displayed in contour plots as functions of selected structural parameters and atomic volume. It turns out that the LDA calculation with SO interaction incorporated provides best agreement with existing experimental data and that the simple cubic structure of a-Po is stabilized by relativistic effects of core electrons. High elastic anisotropy of a-Po is explained as a consequence of its simple cubic structure and is compared with elastic properties of other crystal structures. Finally, an uniaxial tensile test for loading along the [001] and [111] directions is simulated; the corresponding theoretical tensile strengths calculated within the LDA+SO approach amount to 4.2 GPa and 4.7 GPa, respectively, which are the lowest values predicted in an element so far. According to Pugh and Frantsevich criteria, a-Po is predicted to be ductile. Also a positive value of the Cauchy pressure confirms the metallic type of interatomic bonding.
机译：利用全能线性化增强平面波方法，我们研究了Po在其基态简单立方结构（α-Po）中相对于Se和Te呈现的三角螺旋结构的稳定性，以及相变相转变成任一相的稳定性四方相或三角相。借助状态密度，电子能带结构和竞争性高能结构的总能量（对应于总能量的选定固定点）来分析a-Po的相稳定性的起源。 “电子结构”和总能量都是在交换相关能量的广义梯度近似和局部密度近似（LDA）内以及有或没有自旋轨道（SO）耦合的情况下计算的。总能量为在等高线图中显示为所选结构参数和原子量的函数。结果表明，结合了SO相互作用的LDA计算与现有实验数据提供了最佳一致性，并且a-Po的简单立方结构通过核心电子的相对论效应得以稳定解释了a-Po的高弹性各向异性是由于其简单的立方结构，并与其他晶体结构的弹性进行了比较，最后，模拟了沿[001]和[111]方向的单轴拉伸试验；在LDA + SO方法中计算出的相应理论抗拉强度分别为4.2 GPa和4.7 GPa，分别为t到目前为止，该元素中预测的最低值。根据Pugh和Frantsevich的标准，a-Po预计具有延性。柯西压力的正值也证实了原子间键合的金属类型。

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  • 来源
    《Physical review》 |2010年第21期|P.214118.1-214118.19|共19页
  • 作者

    Dominik Legut; Martin Friak; Mojmir Sob;

  • 作者单位

    Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Zizkova 22, CZ-616 62 Brno, Czech Republic Faculty of Chemistry, Brno University of Technology, Purkynova 118, CZ-612 00 Brno, Czech Republic;

    rnInstitute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Zizkova 22, CZ-616 62 Brno, Czech Republic Institute of Condensed Matter Physics, Faculty of Science, Masaryk University, Kotldfskd 2, CZ-611 37 Brno, Czech Republic;

    rnDepartment of Chemistry, Faculty of Science, Masaryk University, Kotldfskd 2, CZ-611 37 Brno, Czech Republic Institute of Physics of Materials, Academy of Sciences of the Czech Republic, v.v.i., Zizkova 22, CZ-616 62 Brno, Czech Republic;

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  • 正文语种 eng
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  • 关键词

    total energy and cohesive energy calculations; relativistic effects; spin-orbit coupling, zeeman and stark splitting, jahn-teller effect;

    机译：总能量和内聚能计算;相对论效应;自旋轨道耦合;塞曼和斯塔克分裂;詹-泰勒效应;

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