Zangi Ronen, Mackowiak Stephan A, Kaufman Laura J
Department of Chemistry, Columbia University, New York, New York 10027, USA.
J Chem Phys. 2007 Mar 14;126(10):104501. doi: 10.1063/1.2434969.
The authors present results from molecular dynamics simulations on the effect of smooth and rough probes on the dynamics of a supercooled Lennard-Jones (LJ) mixture. The probe diameter was systematically varied from one to seven times the diameter of the large particles of the LJ mixture. Mean square displacements show that in the presence of a large smooth probe the supercooled liquid speeds up, while in the presence of a large rough probe, the supercooled liquid slows down. Non-Gaussian parameters indicate that with both smooth and rough probes, the heterogeneity of the supercooled system increases. From the analysis of local Debye-Waller factors, it is evident that the change in the dynamics of the LJ system is heterogeneous, with the largest perturbations close to the probes. Large smooth and rough probes appear to set up heterogeneities in these supercooled systems that would otherwise not occur, and these heterogeneities persist for long times.
作者展示了分子动力学模拟的结果，该模拟研究了光滑和粗糙探针对过冷的 Lennard-Jones（LJ）混合物动力学的影响。探针直径系统地从 LJ 混合物大颗粒直径的 1 倍变化到 7 倍。均方位移表明，在存在大的光滑探针时，过冷液体加速，而在存在大的粗糙探针时，过冷液体减速。非高斯参数表明，无论是光滑探针还是粗糙探针，过冷系统的非均匀性都会增加。从局部德拜-瓦勒因子的分析可以明显看出，LJ 系统动力学的变化是不均匀的，在靠近探针处扰动最大。大的光滑和粗糙探针似乎在这些过冷系统中建立了原本不会出现的非均匀性，并且这些非均匀性会长期持续存在。
