Three-Dimensional RISM Integral Equation Theory for Polarizable Solute Models
Three-Dimensional RISM Integral Equation Theory for Polarizable Solute Models
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DOI：
10.1021/ct400699q
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发表时间：
2013-11-01
影响因子：
5.5
通讯作者：
Kast, Stefan M.
中科院分区：
文献类型：
--
作者：
Hoffgaard, Franziska;Heil, Jochen;Kast, Stefan M.
模拟溶质极化率是改善溶剂化现象描述的关键因素。近年来，可极化分子力力场应运而生，它通过使其静电势分布适应极化环境的能力来绕过经典固定电荷力场的限制。溶剂化现象的特征是溶质的过量化学势，这可以通过昂贵的全原子自由能模拟来计算。另一种选择是采用隐式溶剂模型，这对在可极化框架内建立溶质-溶剂相互作用项提出了挑战。在这里，我们采用三维参考相互作用点模型(3DRISM)积分方程理论作为溶剂模型，解析地产生化学势，并使用嵌入集团(EC-RISM)策略将可极化的阿米巴力场(EC-RISM)。这种方法类似于我们早先将量子化学溶质描述与经典的3D RISM溶剂耦合的方法。我们描述了概念、物理和算法基础，以及几个基准案例的性能作为原则证明。结果一致地表明，变形虫和一般溶液中的量子化学自由能之间有合理的一致性，并允许分开评估能量和溶剂化相关的贡献。我们发现，依赖于参数化，阿米巴重现的化学势与参考量子化学计算比分子内能量更符合，这表明了系统改进可极化力场的可能途径。
Modeling solute polarizability is a key ingredient for improving the description of solvation phenomena. In recent years, polarizable molecular mechanics force fields have emerged that circumvent the limitations of classical fixed charge force fields by the ability to adapt their electrostatic potential distribution to a polarizing environment. Solvation phenomena are characterized by the solute's excess chemical potential, which can be computed by expensive fully atomistic free energy simulations. The alternative is to employ an implicit solvent model, which poses a challenge to the formulation of the solute-solvent interaction term within a polarizable framework. Here, we adapt the three-dimensional dimensional reference interaction site model (3D RISM) integral equation theory as a solvent model, which analytically yields the chemical potential, to the polarizable AMOEBA force field using an embedding cluster (EC-RISM) strategy. The methodology is analogous to our earlier approach to the coupling of a quantum-chemical solute description with a classical 3D RISM solvent. We describe the conceptual physical and algorithmic basis as well as the performance for several benchmark cases as a proof of principle. The results consistently show reasonable agreement between AMOEBA and quantum-chemical free energies in solution in general and allow for separate assessment of energetic and solvation-related contributions. We find that, depending on the parametrization, AMOEBA reproduces the chemical potential in better agreement with reference quantum-chemical calculations than the intramolecular energies, which suggests possible routes toward systematic improvement of polarizable force fields.