DNRF Centre Glass and Time, IMFUFA, Department of Sciences, Roskilde University, Postbox 260, DK-4000 Roskilde, Denmark.
J Chem Phys. 2011 Oct 7;135(13):134501. doi: 10.1063/1.3643123.
The traditional view that the physical properties of a simple liquid are determined primarily by its repulsive forces was recently challenged by Berthier and Tarjus, who showed that in some cases ignoring the attractions leads to large errors in the dynamics [L. Berthier and G. Tarjus, Phys. Rev. Lett. 103, 170601 (2009); J. Chem. Phys. 134, 214503 (2011)]. We present simulations of the standard Lennard-Jones liquid at several condensed-fluid state points, including a fairly low density state and a very high density state, as well as simulations of the Kob-Andersen binary Lennard-Jones mixture. By varying the range of the forces via a shifted-forces cutoff, results for the thermodynamics, dynamics, and structure show that the determining factor for getting the correct statics and dynamics is not whether or not the attractive forces per se are included in the simulations. What matters is whether or not interactions are included from all particles within the first coordination shell - the attractive forces can thus be ignored, but only at extremely high densities. The recognition of the importance of a local shell in condensed fluids goes back to van der Waals; our results confirm this idea and thereby the basic picture of the old hole and cell theories for simple condensed fluids.
传统观点认为，简单液体的物理性质主要由其斥力决定。然而，Berthier 和 Tarjus 最近提出挑战，他们表明在某些情况下，忽略吸引力会导致动力学中出现较大误差 [L. Berthier 和 G. Tarjus, Phys. Rev. Lett. 103, 170601 (2009); J. Chem. Phys. 134, 214503 (2011)]。我们模拟了标准 Lennard-Jones 液体在几个凝聚态流体状态点的情况，包括相当低的密度状态和非常高的密度状态，以及 Kob-Andersen 二元 Lennard-Jones 混合物的模拟。通过改变力的范围（通过移位力截止），热力学、动力学和结构的结果表明，获得正确的静态和动态的决定因素不是模拟中是否包括吸引力本身。重要的是是否包括第一层配位壳内的所有粒子的相互作用——因此吸引力可以忽略，但仅限于极高的密度。在凝聚态流体中局部壳的重要性可以追溯到 van der Waals；我们的结果证实了这一观点，从而也证实了简单凝聚态流体旧的孔和胞理论的基本观点。
