过冷粘性液体中小尺度密度涨落的统计。

Statistics of small length scale density fluctuations in supercooled viscous liquids.

机构信息

Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark.

出版信息

J Chem Phys. 2019 Mar 7;150(9):094505. doi: 10.1063/1.5080277.

DOI:10.1063/1.5080277

PMID:30849876

Abstract

Many successful theories of liquids near the melting temperature assume that small length scale density fluctuations follow Gaussian statistics. This paper presents a numerical investigation of density fluctuations in the supercooled viscous regime using an enhanced sampling method. Five model systems are investigated: the single component Lennard-Jones liquid, the Kob-Andersen binary mixture, the Wahnström binary mixture, the Lewis-Wahnström model of ortho-terphenyl, and the TIP4P/Ice model of water. The results show that the Gaussian approximation persists to a good degree into the supercooled viscous regime; however, it is less accurate at low temperatures. The analysis suggests that non-Gaussian fluctuations are related to crystalline configurations. Implications for theories of the glass transition are discussed.

摘要

许多成功的接近熔化温度的液体理论假设小尺度密度涨落遵循高斯统计。本文使用增强采样方法对过冷粘性区的密度涨落进行了数值研究。研究了五个模型体系：单组分 Lennard-Jones 液体、Kob-Andersen 二元混合物、Wahnström 二元混合物、Lewis-Wahnström 邻三联苯模型和 TIP4P/Ice 水模型。结果表明，在过冷粘性区，高斯近似在很大程度上仍然成立；然而，在低温下精度较低。分析表明，非高斯涨落与晶体结构有关。讨论了对玻璃转变理论的影响。