硝酸钾电解质溶液的结构和热力学性质的计算机分子模拟

A computer simulation study on structure and thermodynamic property of KNO_3 electrolyte solution

对硝酸钾电解质溶液进行了分子动力学计算机模拟研究。水分子采用简单点电荷(SPC)三节点模型,钾离子被看作带电硬球,硝酸根离子采用刚性四节点模型,同时考虑节点间的库仑长程作用和L-J相互作用,对库仑长程作用采用EWALD求和方法进行计算。研究结果表明,随着溶液浓度的增加,水-水相互作用的总势能绝对值升高;高浓度溶液中水-水作用能的升高与水分子排列有序化程度的提高有关,即在浓溶液中水分子的偶极取向更加有序化,说明有更多的水分子参与水化。

The computer simulation was performed in the potassium nitrate electrolyte solution using molecular dynamics method. The simple points charged （SPC） three-slte model was adopted for H2O molecule, the potassium ion was treated as hard sphere, and a rigid four-site model was adopted for the nitrate ion. During the simulation, both coulomb long-range interactions and L-J interactions were considered, and the coulomb long-range interaction was calculated using the EWALD sum method. The results show that the absolute value of water-water interaction energy increases with the increase of ionic concentration, which relates to the increase of the order degree. The higher concentration of the solution is, the higher order degree of dipole tropism is, and much more water molecules are attached to ions.