Dutta Biswanath, Ghosh Subhradip
Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam 781039, India.
J Phys Condens Matter. 2009 Mar 4;21(9):095411. doi: 10.1088/0953-8984/21/9/095411. Epub 2009 Feb 9.
Understanding the role of the inter-atomic force constants in lattice dynamics of random binary alloys is a challenging problem. Addressing these inter-atomic interactions accurately is a necessity to obtain an accurate phonon spectrum and to calculate properties from them. Using a combination of ab initio density functional perturbation theory (DFPT) and the itinerant coherent potential approximation (ICPA), an analytic, self-consistent method for performing configuration averaging in random alloys, we model the inter-atomic force constants for Pd(0.96)Fe(0.04) and Pd(0.9)Fe(0.1) alloys based upon the ab initio results and intuitive arguments. The calculated phonon dispersion curves and elastic constants agree very well with the experimental results. Comparison of our results with those obtained in a model potential scheme is also done. The modeling of inter-atomic interactions in random alloys and their roles regarding the phonon-related properties are also discussed in light of these results.
理解原子间力常数在随机二元合金晶格动力学中的作用是一个具有挑战性的问题。准确处理这些原子间相互作用是获得精确声子谱并据此计算性质的必要条件。我们结合从头算密度泛函微扰理论（DFPT）和巡游相干势近似（ICPA）——一种在随机合金中进行构型平均的解析自洽方法，基于从头算结果和直观论据对Pd(0.96)Fe(0.04)和Pd(0.9)Fe(0.1)合金的原子间力常数进行建模。计算得到的声子色散曲线和弹性常数与实验结果非常吻合。我们还将结果与在模型势方案中获得的结果进行了比较。并根据这些结果讨论了随机合金中原子间相互作用的建模及其对声子相关性质的作用。
