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arXiv 2104.05019cond-mat.softphysics.plasm-ph
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二维Yukawa液体中的Fickian非高斯扩散

Fickian yet non-Gaussian diffusion in two-dimensional Yukawa liquids

Zahra Ghannad

摘要:

我们采用分子动力学模拟研究了二维Yukawa液体中的Fickian扩散。我们计算的自范霍夫关联函数$G_s(r,t)$,和自中间散射函数$F_s(k,t)$和比较这些功能从均方位移MSD使用高斯近似。根据这种近似,随时间的线性MSD意味着$G_s(r,t)$和$F_s(k,t)$始终具有高斯行为。令人惊讶的是,我们发现,这些功能偏离高斯在中间的时间尺度,表明高斯近似的失败。此外,我们量化这些偏差的非高斯参数,我们发现,随着液体的温度降低的偏差增加。非高斯行为的起源可能是在二维汤川液体中观察到的尘埃粒子的非均匀动力学。

英文摘要:

We investigate Fickian diffusion in two-dimensional (2D) Yukawa liquids using molecular dynamics simulations. We compute the self-van Hove correlation function $G_s(r,t)$, and the self-intermediate scattering function $F_s(k,t)$ and compare these functions with those obtained from mean-squared displacement MSD using the Gaussian approximation. According to this approximation, a linear MSD with time implies a Gaussian behavior for $G_s(r,t)$ and $F_s(k,t)$ at all times. Surprisingly, we find that these functions deviate from Gaussian at intermediate time scales, indicating the failure of the Gaussian approximation. Furthermore, we quantify these deviations by the non-Gaussian parameter, and we find that the deviations increase with decreasing the temperature of the liquid. The origin of the non-Gaussian behavior may be the heterogeneous dynamics of dust particles observed in 2D Yukawa liquids.

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