Marenich Aleksandr V, Olson Ryan M, Chamberlin Adam C, Cramer Christopher J, Truhlar Donald G
Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant Street S.E., Minneapolis, Minnesota 55455-0431.
J Chem Theory Comput. 2007 Nov;3(6):2055-67. doi: 10.1021/ct7001539.
Polarization effects in aqueous and nonaqueous solutions were analyzed for nine neutral and three charged organic solutes by the SM8 universal implicit solvation model and class IV partial atomic charges based on Charge Model 4M (CM4M) with the M06-2X density functional. The CM4M partial atomic charges in neutral and ionic solutes and in the corresponding clustered solutes (supersolutes), which included one solute molecule and one or two solvent molecules, were modeled in three solvents (benzene, methylene chloride, and water) and compared to those in the gas phase. The use of the supersolute approach (microsolvation) allows one to account for charge transfer from the solute to the solvent, and we find charge transfers as large as 0.06 atomic units for neutral solutes (pyridine in water) and 0.32 atomic units for ions (methoxide anion in water). Relaxation of the electronic structure of the solute in the presence of solvent increases the polarization free energy of the neutral solutes studied here, on average, by 16% in benzene, 30% in methylene chloride, and 43% in water. The increase for the ions in water averaged 43%.
采用SM8通用隐式溶剂化模型和基于电荷模型4M（CM4M）的IV类部分原子电荷，结合M06 - 2X密度泛函，对9种中性和3种带电有机溶质在水溶液和非水溶液中的极化效应进行了分析。在三种溶剂（苯、二氯甲烷和水）中，对中性和离子溶质以及相应的簇状溶质（超溶质，包括一个溶质分子和一个或两个溶剂分子）中的CM4M部分原子电荷进行了建模，并与气相中的电荷进行了比较。使用超溶质方法（微溶剂化）能够考虑从溶质到溶剂的电荷转移，我们发现中性溶质（水中的吡啶）的电荷转移高达0.06原子单位，离子（水中的甲氧基阴离子）的电荷转移高达0.32原子单位。在此研究的中性溶质在溶剂存在下电子结构的弛豫使极化自由能平均增加，在苯中增加16%，在二氯甲烷中增加30%，在水中增加43%。水中离子的增加平均为43%。
