冷速压力对玻璃化温度和径向分布函数的作用

采用分子动力学的模拟方法计算了水在依次降温,中间充分弛豫的降温过程以及同时对直接降温到某个温度,未足够弛豫的过程的径向分布函数(radial distribution function,RDF)曲线。在依次冷却方式下,选取了5种压力以研究压力对玻璃化温度和径向分布函数的影响;在每个温度段选取了5种冷速以研究依次冷却方式下不同温度段的冷速对径向分布函数的影响。同时对两种降温方式的结果进行了比较。结果表明:降温均匀,静止的水体系玻璃化温度可以大大提高,同时冷速对其玻璃化温度影响不大;压力对玻璃化温度影响不大;证实影响玻璃化温度的主要因素是传热;不同冷速对体系的RDF有影响,但缩小温差并采取中间温度充分驰豫的方式可减小这种差异。

Effect on vitrifying temperatures and radial distribution function by cooling rate and pressure

Simulations were carried out for uniformed-cooled static water by the way of cooling to a final temperature directly and cooling in a sequence with enough relaxtion in mid-temperature points. When cooling in sequence,we calculated effects by five pressures and five cooling rates of temperatrure space on vitrifying temperature and RDF. Meanwhile,we compared results of these two cooling way. The results show that vitrifying temperature of simulated water bulk are both high ,cooling rate and pressure has weak effect on vitrifying temperature, confirming that heat transfer is critical to vitrifying temperature. We also find different cooling rates have great effects on RDF, and structures, but reducing temperature difference with enough relaxtion in mid-temperature points can lower this effects.