在水的大型MD模型中,速度自相关函数的温度行为
A V Anikeenko1, Yu I Naberukhin1
1Voevodsky Institute of Chemical Kinetics and Combustion SB RAS, 630090 Novosibirsk, Russia.
The Journal of chemical physics
|September 26, 2024
概括
这项研究表明,水是水.
科学领域:
- 物理化学 物理化学
- 计算化学的计算化学
- 软物质物理学 软物质物理学
背景情况:
- 了解水的动态在各种科学领域至关重要.
- 速度自相关函数 (VACF) 提供了对分子运动的洞察力.
- 以前的研究已经探索了水的动态,但长期的尾巴行为需要进一步调查.
研究的目的:
- 在水模型中准确计算和分析VACF的长时间尾巴.
- 为了研究VACF长期尾巴的温度依赖性.
- 与简单液体相比,确定水的VACF尾巴的独特特征.
主要方法:
- 使用TIP4P/2005和SPC/E水模型进行了分子动力学模拟.
- 大型系统尺寸 (157,464个分子) 用于高精度.
- 在250370 K的温度范围内计算VACF.
主要成果:
- 长时间的VACF尾巴从高温的水力动力学 (类似) 转变为低温的超冷液态.
- 尾部 (210 ps) 是通过 A*t^(-3/2) - B*t^(-2) 进行的.
- 水力动力学术语 (A) 随着温度的下降而减小,使得 -B*t^(-2) 术语占主导地位,并且是水的独一无二.
结论:
- 水的VACF长期尾巴在低温下表现出明显的负功率法衰变 (-Bt^-2),使其与简单的液体有所区别.
- 这种独特的衰变归因于水力动力学和超冷却液体类行为之间的相互作用.
- 振幅B显示温度稍微增加,并且在中间时间尺度 (0.52 ps) 出现了减弱的振荡.
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