基于第一原理力场预测热力学参数的探讨  

Predictions of thermodynamics parameters based on first-principle force field methods

作　　者：孙淮[1] 武传杰[1] 李晓锋[1] 戴建兴[1] 

机构地区：[1]上海交通大学化学化工学院,上海200240

出　　处：《化工学报》2006年第5期1055-1063,共9页CIESC Journal

基　　金：国家自然科学基金项目(20473052).~~

摘　　要：讨论用第一原理全原子力场计算热力学参数的可行性.新开发的TEAM力场,在用气、液相基本性质验证后,不加任何参数调整,直接用于计算具有代表性的几个分子液体在不同热力学状态下的密度、蒸发焓、混合焓、亨利常数、饱和蒸气压等热力学参数.初步结果表明:液体密度和蒸发焓的预测结果良好,在较大范围内可获得与实验数据相吻合的结果;而混合焓的准确预测需要纯液体内聚能的高精度模拟数据;亨利常数的计算对液体的密度极为敏感.后两种性质的计算均可用全原子力场但需要高质量的力场参数.为了采用全原子力场计算气液相平衡数据,提出了一种半经验的、基于积分Clausius Clapeyron方程的循环自洽方法计算液体的饱和蒸气压.The feasibility of using all-atom, first-principle force fields to predict thermodynamic properties was discussed. A newly developed TEAM force field was used to calculate fluid densities, vaporization enthalpies, heats of mixing, Henry＇s law constants, and vapor pressures for representative molecules in various thermodynamic states. The force field was validated by using the thermodynamic data of gas and liquid phases, and then used to make predictions without any empirical adjustment. Initial results indicated that predictions of liquid densities and vaporization enthalpies were successful. The results comparable with experimental measurements could be obtained at extended state points. The prediction of heats of mixing required very high accuracy in evaluating cohesive energies for pure fluids, and the calculation of Henry＇s law constants was extreme sensitive to fluid densities. Both required high quality of the force fields parameters. In order to calculate the vapor pressures and liquid-vapor coexistence densities effectively with the all atom force fields, a new iterative procedure based on integration of the Clausius- lapeyron equation was proposed.

关 键 词：力场 分子模拟 热力学参数 

分 类 号：TQ015.9[化学工程] O414.2[理学—理论物理]