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arXiv 1504.00809cond-mat.soft
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吸引力在确定简单液体平衡结构和动力学中的作用

Role of attractive forces in determining the equilibrium structure and dynamics of simple liquids

S. Toxvaerd

摘要:

分子动力学模拟结果表明,在不同的吸引力范围内,Lennard-Jones系统中粒子的径向分布随吸引力的变化而改变.仅对于冷凝液体,第一配位壳层(FCS)内的力是重要的,但对于气体和中等冷凝流体,甚至FCS外的吸引力也起作用。由于忽略吸引力而引起的分布变化导致过高的压力。这种微弱的长程引力抑制了气体、超临界流体和液体中粒子的动力学和扩散。自扩散系数(SDC)的值同意定性与修改的科恩-特恩布尔模型。沿临界等温线的SDC-s在临界点处没有显示异常,与实验数据一致。

英文摘要:

Molecular Dynamics simulations of a Lennard-Jones system with different range of attraction show that the attractive forces modify the radial distribution of the particles. For condensed liquids only, the forces within the the first coordination shell (FCS) are important, but for gases and moderate condensed fluids, even the attractive forces outside the FCS play a role. The changes in the distribution caused by neglecting the attractive forces, lead to a too high pressure. The weak long-range attractions damp the dynamics and the diffusion of the particles in gas-, super critical fluid- and in liquid states. The values of self-diffusion coefficients (SDC) agree qualitatively with a modified Cohen-Turnbull model. The SDC-s along the critical isotherm show no anomaly at the critical point in agreement with experimental data.

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