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首页> 外文期刊>Physica, B. Condensed Matter >Ab initio study of the elastic properties of sodium chloride at high pressure
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Ab initio study of the elastic properties of sodium chloride at high pressure

机译：从头开始研究氯化钠在高压下的弹性

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The equation of state and elastic properties for B1- and B2-NaCl up to 160 GPa have been studied by using the density functional simulation within the generalized gradient approximation (GGA). The calculated lattice constants of NaCl agree well with experimental values in a precision of 0.1% over the pressure range studied. It is found that the cell volume decreases 5.5% at the phase transition point. All three independent elastic stiffness coefficients, c_(11), c_(12) and c_(44) for B1- and B2-NaCl are evaluated by a calculated stress tensor which was generated by forcing small strain to the optimized unit cell. The calculated zero-pressure elastic moduli, wave velocities, and their initial pressure dependences of B1-NaCl are in excellent agreement with experiments. Systematic investigation on the elasticity of NaCl has been done through four parameters, the Zener anisotropy ratio (A_Z), the acoustic anisotropy factor (A_a), the Cauchy deviation (δ), and the normalized elastic constants (c_(ij)). With the pressure, the Zener anisotropy ratio A_Z decreases in the B1-phase, but increases in the B2-phase and reaches 1 at about 174 GPa, it suggests that NaCl would become elastic isotropic at this pressure range. The acoustic anisotropy factor A_a shows the similar pressure behavior as A_Z. The Cauchy deviation (δ)) increases with pressures, it demonstrates that in the interatomic interaction, the many-body contribution becomes more important at higher pressures. A discussion on the normalized elastic constants is also presented.
机译：通过使用广义梯度近似（GGA）中的密度泛函模拟研究了高达160 GPa的B1-和B2-NaCl的状态方程和弹性特性方程。在所研究的压力范围内，NaCl的晶格常数的计算值与实验值非常吻合，精度为0.1％。发现在相变点处的晶胞体积减少5.5％。 B1-和B2-NaCl的所有三个独立的弹性刚度系数c_（11），c_（12）和c_（44）通过计算的应力张量进行评估，该应力张量是通过向优化的晶胞施加小的应变而生成的。 B1-NaCl的零压力弹性模量，波速及其初始压力相关性与实验非常吻合。通过四个参数，齐纳各向异性系数（A_Z），声学各向异性系数（A_a），柯西偏差（δ）和归一化弹性常数（c_（ij））对NaCl的弹性进行了系统研究。随着压力的增加，齐纳各向异性比A_Z在B1相减小，但在B2相增大，并在174 GPa左右达到1，这表明NaCl在该压力范围内将变为弹性各向同性。声学各向异性因子A_a显示出与A_Z类似的压力行为。柯西偏差（δ）随压力增加而增加，这表明在原子间相互作用中，多体贡献在较高压力下变得更加重要。还对归一化弹性常数进行了讨论。

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