Smirnov N A
Russian Federal Nuclear Center-Institute of Technical Physics, 456770, Snezhinsk, Russia.
J Phys Condens Matter. 2017 Mar 15;29(10):105402. doi: 10.1088/1361-648X/aa58ca. Epub 2017 Jan 11.
The paper presents first-principles FP-LMTO calculations on the relative stability of fcc, bcc, hcp and dhcp gold under pressure. They were done in local density approximation (LDA), as well as in generalized gradient approximation (GGA) with and without spin-orbit interaction. Phonon spectra for the considered gold structures were obtained from LDA calculations within linear response theory and the contribution of lattice vibrations to the free energy of the system was determined in quasiharmonic approximation. Our thorough adjustment of FP-LMTO internal parameters (linearization and tail energies, the MT-sphere radius) helped us to obtain results that agree well with the available experimental phase relation Dubrovinsky et al (2007 Phys. Rev. Lett. 98 045503) between fcc and hcp structures of gold under pressure. The calculations suggest that gold compressed at room temperature successively undergoes the following structural changes: [Formula: see text]. The paper also presents the calculated elastic constants of fcc, bcc and hcp Au, the principal Hugoniot and the melting curve. Calculated results were used to construct the PT-diagram which describes the relative stability of the gold structures under study up to 500 GPa.
本文介绍了基于第一性原理的全势线性缀加平面波（FP-LMTO）计算，研究了面心立方（fcc）、体心立方（bcc）、六方密堆积（hcp）和双六方密堆积（dhcp）金在压力下的相对稳定性。计算分别采用局域密度近似（LDA）以及考虑和不考虑自旋轨道相互作用的广义梯度近似（GGA）。通过线性响应理论下的LDA计算得到了所考虑金结构的声子谱，并在准谐近似下确定了晶格振动对系统自由能的贡献。我们对FP-LMTO内部参数（线性化和尾部能量、 muffin-tin球半径）的全面调整，使我们得到的结果与现有实验关于金在压力下fcc和hcp结构之间的相关系（Dubrovinsky等人，2007年，《物理评论快报》98 045503）吻合良好。计算表明，室温下压缩的金依次经历以下结构变化：[公式：见原文]。本文还给出了fcc、bcc和hcp金的计算弹性常数、主雨贡纽曲线和熔化曲线。计算结果用于构建PT图，该图描述了所研究金结构在高达500 GPa压力下的相对稳定性。
