Laboratoire Structure, Propriétés et Modélisation des Solides, UMR 8580, École Centrale Paris, Grande Voie des Vignes, F-92295 Chatenay-Malabry, France.
J Phys Condens Matter. 2011 Feb 2;23(4):045502. doi: 10.1088/0953-8984/23/4/045502. Epub 2011 Jan 12.
We have performed density-functional theory calculations for three crystallographic phases (cuprite, CdI(2), and CdCl(2)) of the cuprous oxide by using both the local-density approximation (LDA) and the Perdew-Burke-Ernzerhof generalized-gradient approximation. The latter gives a very good description of the properties of the cuprite phase at room temperature. In particular, the bulk modulus and the elastic constants at zero pressure are in excellent agreement with experiment. At 10 GPa (7 in LDA calculations), the transition from the cuprite to the CdI(2) phase occurs, and the latter remains the phase having the smallest Gibbs energy up to the maximum pressure we have considered (20 GPa). We have also determined the elastic constants of Cu(2)O in the cuprite phase for various applied pressures. The results indicate that this structure becomes unstable with respect to trigonal deformations before the transition to the CdI(2) phase. On the other hand, no indication of instability with respect to tetragonal deformations has been found. This kind of instability would occur at pressures greater than the phase transition pressure.
我们使用局域密度近似（LDA）和 Perdew-Burke-Ernzerhof 广义梯度近似（GGA）对氧化亚铜的三种晶相（赤铜矿、CdI(2)和 CdCl(2)）进行了密度泛函理论计算。后者非常好地描述了室温下赤铜矿相的性质。特别是，零压下的体弹模量和弹性常数与实验非常吻合。在 10 GPa（LDA 计算为 7）时，赤铜矿相到 CdI(2)相的转变发生，后者在我们考虑的最大压力（20 GPa）下仍然是吉布斯自由能最小的相。我们还确定了赤铜矿相中 Cu(2)O 在各种施加压力下的弹性常数。结果表明，在向 CdI(2)相转变之前，这种结构相对于三角变形变得不稳定。另一方面，没有发现相对于四方变形不稳定的迹象。这种不稳定性将发生在相变压力以上的压力下。
