Jin Jaehyeok, Lee Eok Kyun, Voth Gregory A
Department of Chemistry, Chicago Center for Theoretical Chemistry, Institute for Biophysical Dynamics, and James Franck Institute, The University of Chicago, Chicago, Illinois 60637, USA.
Department of Chemistry, Columbia University, New York, New York 10027, USA.
J Chem Phys. 2023 Oct 28;159(16). doi: 10.1063/5.0167158.
This paper series aims to establish a complete correspondence between fine-grained (FG) and coarse-grained (CG) dynamics by way of excess entropy scaling (introduced in Paper I). While Paper II successfully captured translational motions in CG systems using a hard sphere mapping, the absence of rotational motions in single-site CG models introduces differences between FG and CG dynamics. In this third paper, our objective is to faithfully recover atomistic diffusion coefficients from CG dynamics by incorporating rotational dynamics. By extracting FG rotational diffusion, we unravel, for the first time reported to our knowledge, a universality in excess entropy scaling between the rotational and translational diffusion. Once the missing rotational dynamics are integrated into the CG translational dynamics, an effective translation-rotation coupling becomes essential. We propose two different approaches for estimating this coupling parameter: the rough hard sphere theory with acentric factor (temperature-independent) or the rough Lennard-Jones model with CG attractions (temperature-dependent). Altogether, we demonstrate that FG diffusion coefficients can be recovered from CG diffusion coefficients by (1) incorporating "entropy-free" rotational diffusion with translation-rotation coupling and (2) recapturing the missing entropy. Our findings shed light on the fundamental relationship between FG and CG dynamics in molecular fluids.
本系列论文旨在通过超额熵标度（在第一篇论文中引入）建立细粒度（FG）和粗粒度（CG）动力学之间的完整对应关系。虽然第二篇论文利用硬球映射成功捕捉了CG系统中的平动，但单位点CG模型中不存在转动，这导致FG和CG动力学之间存在差异。在这第三篇论文中，我们的目标是通过纳入转动动力学，从CG动力学中忠实地恢复原子扩散系数。通过提取FG转动扩散，我们首次发现了转动扩散和平动扩散之间超额熵标度的普遍性。一旦将缺失的转动动力学纳入CG平动动力学，有效的平动 - 转动耦合就变得至关重要。我们提出了两种不同的方法来估计这个耦合参数：具有偏心因子的粗糙硬球理论（与温度无关）或具有CG吸引力的粗糙 Lennard - Jones模型（与温度有关）。总之，我们证明了可以通过（1）将“无熵”转动扩散与平动 - 转动耦合相结合，以及（2）重新捕捉缺失的熵，从CG扩散系数中恢复FG扩散系数。我们的研究结果揭示了分子流体中FG和CG动力学之间的基本关系。
