论文标题

使用叠加近似(IS-SPA)的隐式溶剂化:氯仿中极性溶质的扩展

Implicit Solvation Using the Superposition Approximation (IS-SPA): Extension to Polar Solutes in Chloroform

论文作者

Lake, Peter T., Mattson, Max A., McCullagh, Martin

论文摘要

在分子模拟领域,有效,准确和适应性的隐式溶剂模型仍然是一个重大挑战。最新的隐式溶剂模型IS-SPA基于使用叠加近似值近似平均溶剂力的基础,为实现这些目标提供了一个平台。 IS-SPA最初是为处理TIP3P水模型中的非极性溶质而开发的,但可以扩展以准确处理其他极性溶剂中的极性溶质。在此手稿中,我们演示了如何适应IS-SPA,以在氯仿的溶剂中包括溶剂方向和长范围的静电处理。氯仿的方向近似为在平均静电场中排列的理想偶极子的方向。然后,将溶剂 - 液压视为平均径向对称的Lennard-Jones组件,并且通过八极术语将静电组件的多极扩展。该模型的参数包括基于原子的溶剂密度和平均电场函数,这些函数符合独立原子或分子的显式溶剂模拟。使用这些参数,IS-SPA解释了电荷溶剂化的不对称性,并重现了两个具有高忠诚度的双电荷Lennard-Jones球的二聚作用的平均力潜力。此外,该模型更准确地捕获了显式溶剂对氯仿中丙氨酸二肽单体和二聚体构型的影响,而不是概括性或恒定密度介电模型。当前版本的算法有望在低于150 mm的浓度下胜过明确的溶剂模拟,远高于这些材料的典型实验浓度。

Efficient, accurate, and adaptable implicit solvent models remain a significant challenge in the field of molecular simulation. A recent implicit solvent model, IS-SPA, based on approximating the mean solvent force using the superposition approximation, provides a platform to achieve these goals. IS-SPA was originally developed to handle non-polar solutes in the TIP3P water model but can be extended to accurately treat polar solutes in other polar solvents. In this manuscript, we demonstrate how to adapt IS-SPA to include the treatment of solvent orientation and long ranged electrostatics in a solvent of chloroform. The orientation of chloroform is approximated as that of an ideal dipole aligned in a mean electrostatic field. The solvent--solute force is then considered as an averaged radially symmetric Lennard-Jones component and a multipole expansion of the electrostatic component through the octupole term. Parameters for the model include atom-based solvent density and mean electric field functions that are fit from explicit solvent simulations of independent atoms or molecules. Using these parameters, IS-SPA accounts for asymmetry of charge solvation and reproduces the explicit solvent potential of mean force of dimerization of two oppositely charged Lennard-Jones spheres with high fidelity. Additionally, the model more accurately captures the effect of explicit solvent on the monomer and dimer configurations of alanine dipeptide in chloroform than a generalized Born or constant density dielectric model. The current version of the algorithm is expected to outperform explicit solvent simulations for aggregation of small peptides at concentrations below 150 mM, well above the typical experimental concentrations for these materials.

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