Molecular simulation study on K+–Cl− ion pair in geological fluids
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- 作者：Mengjia He ; Xiandong Liu ; Xiancai Lu ; Rucheng Wang
- 关键词：Molecular dynamics ; KCl ; Potential of mean force ; Association constant ; Geometry optimization
- 刊名：Acta Geochimica
- 出版年：2017
- 出版时间：March 2017
- 年：2017
- 卷：36
- 期：1
- 页码：1-8
- 全文大小：
- 刊物主题：Geochemistry;
- 出版者：Science Press
- ISSN：2365-7499
- 卷排序：36
文摘
This paper reports a classical molecular dynamics study of the potential of mean forces (PMFs), association constants, microstructures K+–Cl− ion pair in supercritical fluids. The constrained MD method is used to derive the PMFs of K+–Cl− ion pair from 673 to 1273 K in low-density water (0.10–0.60 g/cm3). The PMF results show that the contact ion-pair (CIP) state is the one most energetically favored for a K+–Cl− ion pair. The association constants of the K+–Cl− ion pair are calculated from the PMFs, indicating that the K+–Cl− ion pair is thermodynamically stable. It gets more stable as T increases or water density decreases. The microstructures of the K+–Cl− ion pair in the CIP and solvent-shared ion-pair states are characterized in detail. Moreover, we explore the structures and stabilities of the KCl–Au(I)/Cu(I) complexes by using quantum mechanical calculations. The results reveal that these complexes can remain stable for T up to 1273 K, which indicates that KCl may act as a ligand complexing ore-forming metals in hydrothermal fluids.