Duvail Magali, Villard Arnaud, Nguyen Thanh-Nghi, Dufrêche Jean-François
Institut de Chimie Séparative de Marcoule (ICSM), UMR 5257, CEA-CNRS-Université Montpellier-ENSCM , Site de Marcoule, Bâtiment 426, BP 17171, F-30207 Bagnols-sur-Cèze Cedex, France.
J Phys Chem B. 2015 Aug 27;119(34):11184-95. doi: 10.1021/acs.jpcb.5b03088. Epub 2015 May 22.
A polarizable force field for the sulfate anion SO4(2–) has been developed and extended from nonpolarizable force fields in order to reproduce its structural and thermodynamics properties in aqueous solution. Two force fields with different atomic partial charges on S and O have been tested and used with molecular dynamics with explicit polarization. The results obtained with our developed force field are in good agreement with the experimental hydration properties of the sulfate anion. In addition to molecular dynamics simulations of the sulfate anion in aqueous solution, potentials of mean force of sulfate electrolytes have been calculated via umbrella-sampling molecular dynamics simulations, i.e., MgSO4, EuSO4(+), and UO2SO4. These potentials allow for calculating pair association constants directly comparable to the experimental ones. In the case of monoatomic cations such as Mg(2+) and Eu(3+), the association constants calculated are in very good agreement with the experimental values, i.e., pKcalc = 2.21 (vs 2.21 experimentally) and 3.86 (vs 3.56–3.78 experimentally) for MgSO4 and EuSO4(+), respectively. In the case of purely molecular electrolyte (UO2SO4), the association constant calculated (pKcalc = 1.58–2.07) is in agreement with the range of values available in the literature (pKexp = 1.17–3.14).
已开发出一种用于硫酸根阴离子SO4(2–)的可极化力场，它是在非极化力场的基础上扩展而来的，目的是再现其在水溶液中的结构和热力学性质。对硫（S）和氧（O）上具有不同原子部分电荷的两种力场进行了测试，并用于具有显式极化的分子动力学。用我们开发的力场获得的结果与硫酸根阴离子的实验水合性质高度吻合。除了对硫酸根阴离子在水溶液中的分子动力学模拟外，还通过伞形采样分子动力学模拟计算了硫酸电解质的平均力势，即MgSO4、EuSO4(+)和UO2SO4。这些势使得能够直接计算与实验值可比的配对缔合常数。对于诸如Mg(2+)和Eu(3+)等单原子阳离子的情况，计算得到的缔合常数与实验值非常吻合，即MgSO4和EuSO4(+)的pKcalc分别为2.21（实验值为2.21）和3.86（实验值为3.56 - 3.78）。对于纯分子电解质（UO2SO4）的情况，计算得到的缔合常数（pKcalc = 1.58 - 2.07）与文献中可用的值范围（pKexp = 1.17 - 3.14）相符。
