The long-time behavior of the velocity autocorrelation function (VACF) is investigated by the molecular dynamics simulation of a two-dimensional system which has both a many-body interaction and a random potential. With strengthening the random potential by increasing the density of impurities, a crossover behavior of the VACF is observed from a positive tail, which is proportional to t^{-1}, to a negative tail, proportional to -t^{-2}. The latter tail exists even when the density of particles is the same order as the density of impurities. The behavior of the VACF in a nonequilibrium steady state is also studied. In the linear response regime the behavior is similar to that in the equilibrium state, whereas it changes drastically in the nonlinear response regime.

速度自相关函数(VACF)的长期行为是 二维系统的分子动力学模拟研究 它既有多体相互作用，又有随机势。使用 通过增加杂质密度来增强无规势，a VACF的交叉行为是从正尾观察的，这是 与t^{-1}成正比，与负尾成正比，与-t^{-2}成正比。后者 即使当粒子的密度与密度相同时，尾部也存在 纯净的东西。VACF在非平衡稳态下的行为是 也进行了研究。在线性响应机制中，行为类似于 平衡状态，而在非线性响应中它发生了剧烈的变化 政权。