方解石水溶液结晶的分子动力学模拟

Molecular Dynamics Simulation on an Aqueous Solution of Calcite

将方解石水溶液看作正则系综,采用分子动力学方法对构建的方解石水溶液进行模拟计算,模拟了温度从273～373K变化时方解石水溶液的结晶情况.通过分析不同温度下的扩散系数,径向分布函数图以及结合能的大小,得出水溶液随着温度的升高,水分子的扩散系数不断增大,Ca2+和CO23-的扩散系数在293K时相对较小,容易结晶.计算了293K时方解石水溶液中的Ca2+和CO32-的径向分布函数,得到在距离为2.1处最容易结晶.另外,通过计算得到方解石在(1-1 0)晶面与Ca2+,CO32-的结合能为-0.38 kcal/mol.

In order to study the calcite crystallization,the aqueous solution of calcite was treated as a canonical ensemble by using Molecular dynamics simulate the calcite system whose temperature ranges from 273 K to 373 K.The conclusions are drew that the diffusion coefficient of water molecules increases ceaselessly with the increasing of the temperature and that the diffusion coefficients of Ca2＋ and CO2-3 are relatively small and the aqueous solution of calcite is easy to crystallize when the temperature is 293 K by analysing the diffusion coefficient and the radial distribution function and the binding energy in different temperature.And it’s also concluded that the aqueous solution of calcite is the easiest to crystalline at the distance of 2.1  by calculating the radial distribution function of Ca2＋ and CO32- when the temperature of aqueous solution of calcite is 293 K.Then it’s calculated that the binding energy between（1-1 0） surface and Ca2＋ and CO32- is-0.38 kcal/mol.