标题： 温度梯度下的长程关联：简单流体的分子动力学研究 显示英文标题

标题： Long-Range Correlations under Temperature Gradients: A Molecular Dynamics Study of Simple Fluids

摘要： 在温度梯度下的流体中，长程关联（LRCs）通常出现，导致密度涨落增强。 这种现象以静态结构因子中的$\boldsymbol{q}^{-4}$发散为特征（其中$\boldsymbol{q}$是波数），已在理论和实验上进行了广泛研究。 然而，在使用分子动力学（MD）模拟的哈密顿粒子系统中，它们仍未被探索。 这封信报告了首次提供明确观测LRCs的MD研究。 我们通过三种不同的方法证明了这一点：（1）测量静态结构因子并直接观察表征LRCs的$\boldsymbol{q}^{-4}$发散；（2）在动态结构因子中检测相应的$\boldsymbol{q}^{-4}$发散；（3）建立MD结果与波动流体力学预测之间的定量一致性，波动流体力学是一种预测LRCs的表观理论。 我们的发现表明，MD模拟为LRCs的理论和实验研究提供了一种强大的补充工具。 显示英文摘要

摘要： In fluids under temperature gradients, long-range correlations (LRCs) emerge generically, leading to enhanced density fluctuations. This phenomenon, characterized by the $\boldsymbol{q}^{-4}$ divergence in the static structure factor (where $\boldsymbol{q}$ is the wavenumber), has been extensively studied both theoretically and experimentally. However, they remain unexplored in Hamiltonian particle systems using molecular dynamics (MD) simulations. This Letter reports the first MD study to provide unambiguous observations of the LRCs. We demonstrate this by three distinct approaches: (1) measuring the static structure factor and directly observing the $\boldsymbol{q}^{-4}$ divergence characterizing the LRCs; (2) detecting the corresponding $\boldsymbol{q}^{-4}$ divergence in the dynamic structure factor; (3) establishing a quantitative agreement between MD results and predictions from fluctuating hydrodynamics, the phenomenological theory that predicts the LRCs. Our findings demonstrate that MD simulations offer a powerful complementary tool to theoretical and experimental investigations of LRCs.