Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
J Chem Phys. 2011 Aug 21;135(7):074504. doi: 10.1063/1.3624656.
A detailed analysis of homogeneous melting in crystalline materials modeled by empirical interatomic potentials is presented using the theory of inherent structures. We show that the homogeneous melting of a perfect, infinite crystalline material can be inferred directly from the growth exponent of the inherent structure density-of-states distribution expressed as a function of formation enthalpy. Interestingly, this growth is already established by the presence of very few homogeneously nucleated point defects in the form of Frenkel pairs. This finding supports the notion that homogeneous melting is appropriately defined in terms of a one-phase theory and does not require detailed consideration of the liquid phase. We then apply this framework to the study of applied hydrostatic compression on homogeneous melting and show that the inherent structure analysis used here is able to capture the correct pressure-dependence for two crystalline materials, namely silicon and aluminum. The coupling between the melting temperature and applied pressure arises through the distribution of formation volumes for the various inherent structures.
本文利用本征结构理论，对基于经验原子间势的晶态材料均匀熔化进行了详细分析。我们表明，通过将本征结构态密度分布的生长指数表示为形成焓的函数，可以直接推断出完美、无限晶态材料的均匀熔化。有趣的是，这种生长仅由少数以弗伦克尔对形式均匀形核的点缺陷存在即可建立。这一发现支持了这样一种观点，即均匀熔化是根据单相理论恰当地定义的，并不需要详细考虑液相。然后，我们将这一框架应用于均匀熔化的静水压力研究，表明这里使用的本征结构分析能够捕捉到两种晶态材料（即硅和铝）的正确压力依赖性。熔化温度与外加压力之间的耦合来自于各种本征结构的形成体积分布。
