Dependence of the fragility of a glass former on the softness of interparticle interactions
Dependence of the fragility of a glass former on the softness of interparticle interactions
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DOI：
10.1063/1.3660201
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发表时间：
2011-11-21
影响因子：
4.4
通讯作者：
Sastry, Srikanth
中科院分区：
文献类型：
--
作者：
Sengupta, Shiladitya;Vasconcelos, Filipe;Sastry, Srikanth
我们研究的影响，考虑三个模型的二元混合物玻璃形成剂的玻璃形成剂的脆性的粒子间相互作用的柔软性。粒子间的相互作用势是一种修正的Lennard-Jones型势，它的排斥部分随粒子间距离的反幂q而变化，吸引部分随粒子间距离的反幂p而变化（模型II）和（8，5）（模型III）对于（q，p），使得相互作用势从模型I到模型III变得更软。我们从扩散系数和弛豫时间的温度变化评估动力学脆弱性，从构型熵的温度变化评估热力学脆弱性。我们发现，动力学的脆弱性增加的潜力，与以前的结果一致，这些模型系统，但在与热力学的脆弱性，这与增加的相互作用的柔软性，以及从早期的结果的预期减少。我们合理化我们的结果，考虑完整形式的亚当-吉布斯关系，这需要，除了温度依赖性的构型熵，知识的高温活化能，以确定脆弱性。我们表明，考虑缩放的高温活化能与液体密度，在最近的研究中分析，提供了部分合理化所观察到的行为。(C)2011年美国物理学会。[doi：10.1063/1.3660201]
We study the influence of the softness of the interparticle interactions on the fragility of a glass former by considering three model binary mixture glass formers. The interaction potential between particles is a modified Lennard-Jones type potential, with the repulsive part of the potential varying with an inverse power q of the interparticle distance, and the attractive part varying with an inverse power p. We consider the combinations (12,11) (model I), (12,6) (model II), and (8,5) (model III) for (q, p) such that the interaction potential becomes softer from model I to III. We evaluate the kinetic fragilities from the temperature variation of diffusion coefficients and relaxation times, and a thermodynamic fragility from the temperature variation of the configurational entropy. We find that the kinetic fragility increases with increasing softness of the potential, consistent with previous results for these model systems, but at variance with the thermodynamic fragility, which decreases with increasing softness of the interactions, as well as expectations from earlier results. We rationalize our results by considering the full form of the Adam-Gibbs relation, which requires, in addition to the temperature dependence of the configurational entropy, knowledge of the high temperature activation energies in order to determine fragility. We show that consideration of the scaling of the high temperature activation energy with the liquid density, analyzed in recent studies, provides a partial rationalization of the observed behavior. (C) 2011 American Institute of Physics. [doi:10.1063/1.3660201]