Department of Biomedical Engineering, Chemistry of Life Processes Institute, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
J Chem Phys. 2013 Jul 28;139(4):044509. doi: 10.1063/1.4816523.
Using extensive molecular dynamics simulations combined with a novel approach to analyze the molecular displacements we analyzed the change in the dynamics above and below the crossover temperature T(x) for supercooled water. Our findings suggest that the crossover from fragile to strong glass former occurring at T(x) is related with a change in the diffusion mechanism evidencing the presence of jump-like diffusion at lower temperatures. Also we observe that fluctuations of the local environments are intimately connected with fluctuations in the size and the amount of cooperative cluster of mobile molecules, and in particular we find a highly cooperative nature of the motion at low temperatures.
利用广泛的分子动力学模拟，并结合一种分析分子位移的新方法，我们分析了过冷水中的动力学在交叉温度 T(x)上下的变化。我们的发现表明，在 T(x)处从脆弱向强玻璃形成体的转变与扩散机制的变化有关，这表明在较低温度下存在类似跳跃的扩散。此外，我们还观察到局部环境的涨落与移动分子的协同簇的大小和数量的涨落密切相关，特别是我们发现低温下运动具有高度协同性。
