Physique Théorique des Matériaux, Institut de Physique, Université de Liège, B-4000 Sart Tilman, Belgium.
J Phys Condens Matter. 2014 Jan 22;26(3):035401. doi: 10.1088/0953-8984/26/3/035401. Epub 2013 Dec 12.
By means of first-principles calculations, various properties of SrRuO3 are investigated, focusing on its lattice dynamical properties. Despite having a Goldschmidt tolerance factor very close to 1, the phonon dispersion curves of the high-temperature cubic phase of SrRuO3 show strong antiferrodistortive instabilities. The energetics of metastable phases with different tilt patterns are discussed, concluding that the coupling of oxygen rotation modes with anti-polar Sr motion plays a key role in stabilizing the Pnma phase with respect to alternative rotation patterns. Our systematic analysis confirms previous expectations and contributes to rationalizing better why many ABO3 perovskites, including metallic compounds, exhibit an orthorhombic ground state. The zone-center phonon modes of the Pnma phase have been computed, from which we propose partial reassignment of available experimental data. The full dispersion curves have also been obtained, constituting benchmark results for the interpretation of future measurements and providing access to thermodynamical properties.
通过第一性原理计算，研究了 SrRuO3 的各种性质，重点研究了其晶格动力学性质。尽管 Goldschmidt 容忍因子非常接近 1，但 SrRuO3 的高温立方相的声子色散曲线显示出强烈的反铁畸变不稳定性。讨论了具有不同倾斜模式的亚稳相的能学，得出结论，氧旋转模式与反极 Sr 运动的耦合在稳定 Pnma 相对于其他旋转模式的相方面起着关键作用。我们的系统分析证实了先前的预期，并有助于更好地说明为什么包括金属化合物在内的许多 ABO3 钙钛矿都表现出正交基态。计算了 Pnma 相的晶心声子模式，从中我们提出了对现有实验数据的部分重新分配。还获得了完整的色散曲线，为未来测量的解释提供了基准结果，并提供了对热力学性质的访问。
