Sweere Augustinus J M, Fraaije Johannes G E M
Soft Matter Chemistry, Leiden University , Einsteinweg 55, 2333CC Leiden, The Netherlands.
J Chem Theory Comput. 2017 May 9;13(5):1911-1923. doi: 10.1021/acs.jctc.6b01106. Epub 2017 Apr 24.
We have calculated the excess free energy of mixing of 1053 binary mixtures with the OPLS-AA force field using two different methods: thermodynamic integration (TI) of molecular dynamics simulations and the Pair Configuration to Molecular Activity Coefficient (PAC-MAC) method. PAC-MAC is a force field based quasi-chemical method for predicting miscibility properties of various binary mixtures. The TI calculations yield a root mean squared error (RMSE) compared to experimental data of 0.132 kT (0.37 kJ/mol). PAC-MAC shows a RMSE of 0.151 kT with a calculation speed being potentially 1.0 × 10 times greater than TI. OPLS-AA force field parameters are optimized using PAC-MAC based on vapor-liquid equilibrium data, instead of enthalpies of vaporization or densities. The RMSE of PAC-MAC is reduced to 0.099 kT by optimizing 50 force field parameters. The resulting OPLS-PM force field has a comparable accuracy as the OPLS-AA force field in the calculation of mixing free energies using TI.
我们使用两种不同方法，采用OPLS - AA力场计算了1053种二元混合物的混合超额自由能：分子动力学模拟的热力学积分（TI）方法和成对构型到分子活度系数（PAC - MAC）方法。PAC - MAC是一种基于力场的准化学方法，用于预测各种二元混合物的混溶性。与实验数据相比，TI计算得出的均方根误差（RMSE）为0.132 kT（0.37 kJ/mol）。PAC - MAC的RMSE为0.151 kT，计算速度可能比TI快1.0×10倍。基于气液平衡数据而非汽化焓或密度，使用PAC - MAC对OPLS - AA力场参数进行了优化。通过优化50个力场参数，PAC - MAC的RMSE降至0.099 kT。所得的OPLS - PM力场在使用TI计算混合自由能时，与OPLS - AA力场具有相当的准确性。
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