电解质溶液自扩散系数的布朗动力学模拟  

Brownian Dynamics Simulation of Self-diffusion Coefficients of Electrolyte Solutions

作　　者：史红兵[1] 于养信[1] 高光华[1] 

机构地区：[1]清华大学化学工程系,北京100084

出　　处：《高等学校化学学报》2004年第12期2317-2321,共5页Chemical Journal of Chinese Universities

基　　金：国家自然科学基金 (批准号 :2 0 1760 2 0 )资助

摘　　要：采用布朗动力学方法对电解质溶液进行了模拟 ,在传统布朗动力学的基础上综合考虑了流体力学的影响 ,并且引入 Smart Monte Carlo方法的接受概率 ,避免了离子不现实的移动和位型重叠 ,这样不仅可以将模拟过程中的时间步长大幅度提高 ,而且还可使溶质在相空间的演化过程更接近实际 .模拟过程以电解质溶液的原始模型为基础 ,将溶剂看作连续介质 ,溶质分子之间的相互作用采用软核加静电的势能函数模型 ,长程静电力采用 Ewald加和的处理方法 .模拟得到 KCl和 Na Cl溶液的径向分布函数 g+ - ( r) ,g+ + ( r)和 g- - ( r) ,并与文献中 HNC计算以及模拟的结果进行比较 ,使用推广的 Green-Kubo公式模拟计算溶液中各种离子的自扩散性质 。Brownian dynamics simulation is carried out to study the electrolyte solution. We take into account the effect of hydrodynamic interactions and combine an acceptance criterion known from the Smart Monte Carlo method with the traditional method. As a result, unrealistic movements are avoided and overlapping configurations are prevented, furthermore, bigger time step can be applied. The solvent-averaged interaction potential between the ions is modeled by pairwise repulsive soft-core interactions and Coulomb forces which is handled by Ewald Summation Technique. The radial distribution function g +-(r), g ++(r) and g --(r) are obtained and compared with that from HNC integral equation and simulations available in literature. Self-diffusion coefficients of ions are obtained with the equivalent Green-Kubo expressions derived from the linear response theory on the Smoluchowski Level. The results are in good agreement with those from experiments.

关 键 词：布朗动力学模拟 电解质溶液 径向分布函数 自扩散系数 

分 类 号：O646[理学—物理化学]