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arXiv 1301.0168cond-mat.mtrl-sciphysics.comp-ph
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各向异性界面超额自由能的从头计算

Ab initio calculation of anisotropic interfacial excess free energies

Axel van de Walle, Chirranjeevi Balaji Gopal, Steve Demers, Qijun Hong, Adam Kowalski, Ljubomir Miljacic, Gregory Pomrehn, Pratyush Tiwary

摘要:

我们描述了一个简单的方法来确定,从头计算,在固态晶体系统中的界面自由能的完整的取向依赖性。我们举例说明的方法与应用程序中的Al-Ti合金系统的沉淀。该方法结合了集群扩展形式主义在其最一般的形式(模拟系统的能量)与反转的著名的武尔夫建设(恢复界面能从平衡沉淀物的形状)。虽然逆Wulff结构只提供了各种界面自由能的相对大小,但绝对自由能可以从单个方便选择的平面界面的计算中恢复。该方法是能够占基本上所有来源的熵(所产生的声子,体点缺陷,以及界面粗糙度),因此能够透明地处理原子光滑和粗糙的界面。该方法表示所得到的取向依赖的界面性能使用的一般取向依赖量的自适应基地。作为一个副产品,本文因此提供了一个简单而通用的方法来生成这样的基函数,这证明是有用的,在各种其他应用中,例如,代表所谓的组分应变弹性能的各向异性。

英文摘要:

We describe a simple method to determine, from ab initio calculations, the complete orientation-dependence of interfacial free energies in solid-state crystalline systems. We illustrate the method with an application to precipitates in the Al-Ti alloy system. The method combines the cluster expansion formalism in its most general form (to model the system's energetics) with the inversion of the well-known Wulff construction (to recover interfacial energies from equilibrium precipitate shapes). Although the inverse Wulff construction only provides the relative magnitude of the various interfacial free energies, absolute free energies can be recovered from a calculation of a single, conveniently chosen, planar interface. The method is able to account for essentially all sources of entropy (arising from phonons, bulk point defects, as well as interface roughness) and is thus able to transparently handle both atomically smooth and rough interfaces. The approach expresses the resulting orientation-dependence of the interfacial properties using symmetry-adapted bases for general orientation-dependent quantities. As a by-product, this paper thus provides a simple and general method to generate such basis functions, which prove useful in a variety of other applications, for instance to represent the anisotropy of the so-called constituent strain elastic energy.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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