第一原则分子动力学模拟大气相关的离子溶解在超冷的水滴中
Yu Zhao1, Hui Li, Xiao Cheng Zeng
1Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States.
Journal of the American Chemical Society
|September 25, 2013
概括
化物离子如化物和化物更喜欢水滴表面,而化物更喜欢散装. 离子没有偏好,这是超冷水模拟中的新发现.
科学领域:
- 物理化学 物理化学
- 计算化学计算化学
- 材料科学 材料科学 材料科学
背景情况:
- 了解离子溶解对于各种化学和生物过程至关重要.
- 超冷水与环境水相比,具有独特的特性,影响溶解行为.
- 有限的数据存在于限制,深度超冷水环境中的化物离子行为.
研究的目的:
- 为了研究化离子 (F-, Cl-, Br-, I-) 在一个封闭的,深度超冷的水滴中的溶解行为.
- 通过第一原则模拟,阐明水合化离子的结构和动态特性.
- 确定化离子在这种特定环境中的独特溶解偏好和动态.
主要方法:
- 综合的第一原则 波恩-奥本海默分子动力学 (BOMD) 模拟.
- 模拟一个直径约为1.8纳米的深超冷水滴.
- 对化物离子 (F-, Cl-, Br-, I-) 位置,协调数,水化结构,扩散系数和停留时间的分析.
主要成果:
- 较大的化离子 (Br-, I-) 显示出外层表面偏好,而F-显示出散装偏好.
- 离子 (Cl-) 在超冷水中没有显著的表面或散装偏好,这是一个新的观察.
- 水结构有所不同:F-形成五倍协调的方形金字塔,而Cl-, Br-和I-形成五倍或六倍协调的三明治状结构.
- 化物 (I-) 显示出最大的扩散系数,但化物 (Br-) 显示出更快的表面接近率从滴体内部.
结论:
- 深度超冷水滴中的化物离子溶解取决于大小,观察到F-, Br-和I-的明显表面或散装偏好.
- 在这种环境中,不寻常的缺乏对Cl-ion的偏好需要进一步调查.
- 离子大小,扩散和表面相互作用动态之间的相互作用是复杂的,并且在化离子之间存在差异.
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