Molecular simulation study on K<Superscript>+</Superscript>–Cl<Superscript>−</Superscript> ion pair in geological fluids     

Mengjia He  Xiandong Liu  Xiancai Lu  Rucheng Wang 《中国地球化学学报》2017,36(1):1-8

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.  相似文献