Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
J Chem Phys. 2011 Aug 28;135(8):084513. doi: 10.1063/1.3627148.
We investigate numerically the structure, thermodynamics, and relaxation behavior of a family of (n, 6) Lennard-Jones-like glass-forming binary mixtures interacting via pair potentials with variable softness, fixed well depth, and fixed well depth location. These constraints give rise to progressively more negative attractive tails upon softening, for separations greater than the potential energy minimum. Over the range of conditions examined, we find only modest dependence of structure on softness. In contrast, decreasing the repulsive exponent from n=12 to n=7 causes the diffusivity to increase by as much as two orders of magnitude at fixed temperature and density, and produces mechanically stable packings (inherent structures) with cohesive energies that are, on average, ∼1.7 well depths per particle larger than for the corresponding Lennard-Jones (n=12) case. The softer liquids have markedly higher entropies and lower Kauzmann temperatures than their Lennard-Jones (n=12) counterparts, and they remain diffusive down to appreciably lower temperatures. We find that softening leads to a modest increase in fragility.
我们通过数值模拟研究了一族（n，6）类 Lennard-Jones 玻璃形成二元混合物的结构、热力学和弛豫行为，这些混合物通过具有可变柔软度、固定深阱和固定深阱位置的对势能相互作用。这些约束条件导致在分离大于势能最小时，吸引力尾部变得越来越负。在所研究的条件范围内，我们发现结构对柔软度的依赖性很小。相比之下，将排斥指数从 n=12 降低到 n=7 会导致在固定温度和密度下扩散率增加多达两个数量级，并产生机械稳定的堆积（本征结构），其结合能平均比相应的 Lennard-Jones（n=12）情况高约 1.7 个阱深。较软的液体具有明显更高的熵和更低的 Kauzmann 温度，比它们的 Lennard-Jones（n=12）对应物要低，并且它们在明显更低的温度下仍然具有扩散性。我们发现柔软度的增加会导致脆性的适度增加。
