Long-time tail of the velocity autocorrelation function in a two-dimensional moderately dense hard-disk fluid.
Long-time tail of the velocity autocorrelation function in a two-dimensional moderately dense hard-disk fluid.
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DOI：
10.1103/physreve.77.021201
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发表时间：
2008-01
期刊：
影响因子：
--
通讯作者：
M. Isobe
中科院分区：
文献类型：
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作者：
M. Isobe
桤木和温赖特利用事件驱动的分子动力学模拟发现了中等密度硬球流体中速度自相关函数的慢功率衰减~t（-d/2）（d为维数）。在二维情况下，利用线性响应理论中的时间相关表达式得到的扩散系数呈现对数发散，这被称为“二维长时尾问题”。“我们重新研究了这个问题，使用现代高效算法对1x 10（6）硬盘进行了大规模的长时间模拟，发现中等密度流体中长尾的衰减略快于功率衰减（~1/t）。在长时间极限[~1/（t sqrt[ln t]）]下，我们还将数值结果与自洽模耦合理论的预测进行了比较。
Alder and Wainwright discovered the slow power decay ~t(-d/2) (d is dimension) of the velocity autocorrelation function in moderately dense hard-sphere fluids using the event-driven molecular dynamics simulations. In the two-dimensional (2D) case, the diffusion coefficient derived using the time correlation expression in linear response theory shows logarithmic divergence, which is called the "2D long-time-tail problem." We reexamined this problem to perform a large-scale, long-time simulation with 1x10(6) hard disks using a modern efficient algorithm and found that the decay of the long tail in moderately dense fluids is slightly faster than the power decay (~1/t) . We also compared our numerical data with the prediction of the self-consistent mode-coupling theory in the long-time limit [~1/(t sqrt[ln t])] .