流体中的原子动力学：重新审视简正模式分析。

Atomic dynamics in fluids: Normal mode analysis revisited.

作者信息

Moon Jaeyun, Lindsay Lucas, Egami Takeshi

机构信息

Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.

Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA; Department of Materials Science and Engineering, University of Tennessee, Knoxville, Tennessee 37996, USA; and Department of Physics and Astronomy, University of Tennessee, Knoxville, Tennessee 37996, USA.

出版信息

Phys Rev E. 2023 Jul;108(1-1):014601. doi: 10.1103/PhysRevE.108.014601.

DOI:10.1103/PhysRevE.108.014601

PMID:37583138

Abstract

Developing microscopic understanding of the thermal properties of liquids is challenging due to their strong dynamic disorder, which prevents characterization of the atomic degrees of freedom. There have been significant research interests in the past few decades to extend the normal mode analysis for solids to instantaneous structures of liquids. However, the nature of normal modes that arise from these unstable structures is still elusive. In this paper, we explore the instantaneous eigenmodes of dynamical matrices of various Lennard-Jones argon liquid and gas systems at high temperatures and show that the normal modes can be interpreted as an interpolation of T→∞ (gas) and T=0 (solid) mode descriptions. We find that normal modes become increasingly collisional and translational, recovering atomistic gaslike behavior rather than vibrational with increase in temperature, suggesting that normal modes in liquids may be described by both solidlike and gaslike modes.

摘要

由于液体存在强烈的动态无序性，难以对其原子自由度进行表征，因此从微观层面理解液体的热性质具有挑战性。在过去几十年里，人们对将固体的简正模式分析扩展到液体的瞬时结构有着浓厚的研究兴趣。然而，这些不稳定结构产生的简正模式的本质仍然难以捉摸。在本文中，我们研究了各种高温下的 Lennard-Jones 氩气液体和气体系统动力学矩阵的瞬时本征模，结果表明简正模式可被解释为 T→∞（气体）和 T = 0（固体）模式描述的一种插值。我们发现，随着温度升高，简正模式越来越具有碰撞性和平动性，呈现出类似原子气体的行为而非振动行为，这表明液体中的简正模式可能由类固体模式和类气体模式共同描述。