Max Planck Institute for Polymer Research, 55128 Mainz, Germany.
J Chem Phys. 2019 Dec 28;151(24):244110. doi: 10.1063/1.5131105.
Coarse-grained (CG) models are often parameterized to reproduce one-dimensional structural correlation functions of an atomically detailed model along the degrees of freedom governing each interaction potential. While cross correlations between these degrees of freedom inform the optimal set of interaction parameters, the correlations generated from the higher-resolution simulations are often too complex to act as an accurate proxy for the CG correlations. Instead, the most popular methods determine the interaction parameters iteratively while assuming that individual interactions are uncorrelated. While these iterative methods have been validated for a wide range of systems, they also have disadvantages when parameterizing models for multicomponent systems or when refining previously established models to better reproduce particular structural features. In this work, we propose two distinct approaches for the direct (i.e., noniterative) parameterization of a CG model by adjusting the high-resolution cross correlations of an atomistic model in order to more accurately reflect correlations that will be generated by the resulting CG model. The derived models more accurately describe the low-order structural features of the underlying AA model while necessarily generating inherently distinct cross correlations compared with the atomically detailed reference model. We demonstrate the proposed methods for a one-site-per-molecule representation of liquid water, where pairwise interactions are incapable of reproducing the true tetrahedral solvation structure. We then investigate the precise role that distinct cross-correlation features play in determining the correct pair correlation functions, evaluating the importance of the placement of correlation features as well as the balance between features appearing in different solvation shells.
粗粒化 (CG) 模型通常是通过对控制每个相互作用势能的自由度的原子细节模型的一维结构相关函数进行参数化来构建的。虽然这些自由度之间的交叉相关信息提供了最佳的相互作用参数集,但来自更高分辨率模拟的相关信息通常过于复杂,无法作为 CG 相关性的准确代理。相反,最流行的方法是在假设各个相互作用是不相关的情况下迭代确定相互作用参数。虽然这些迭代方法已经在广泛的系统中得到了验证,但在对多组分系统进行参数化或改进先前建立的模型以更好地再现特定结构特征时,它们也存在缺点。在这项工作中,我们提出了两种截然不同的方法,通过调整原子模型的高分辨率交叉相关来直接(即非迭代)参数化 CG 模型,以更准确地反映由生成的 CG 模型生成的相关性。所得到的模型更准确地描述了底层 AA 模型的低阶结构特征,同时与原子细节参考模型相比,必然会产生内在不同的交叉相关。我们展示了这些方法在一个分子一个位置的液体水表示中的应用,其中成对相互作用无法再现真实的四面体形溶剂化结构。然后,我们研究了不同交叉相关特征在确定正确的对相关函数方面的确切作用,评估了相关特征的位置以及不同溶剂化壳中出现的特征之间的平衡的重要性。