Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Phys Chem Chem Phys. 2018 Aug 29;20(34):22387-22394. doi: 10.1039/c8cp00746b.
Coarse-graining is a systematic reduction of the number of degrees of freedom used to describe a system of interest. Coarse-graining can be thought of as a projection on the coarse-grained degrees of freedom and is therefore dependent on the number and type of basis functions used to represent the coarse-grained force field. We show that many-body extensions of the coarse-grained force field can result in substantial changes of the two-body interactions, making them much more attractive at short distances. This interplay can be alleviated by first parametrizing the two-body potential and then fitting the additional three-body contribution to the residual forces. The approach is illustrated on liquid water where three-body interactions are essential to reproduce the structural properties, and liquid methanol where two-body interactions are sufficient to reproduce the main structural features of the atomistic system. Furthermore, we demonstrate that the structural and thermodynamic accuracy of the coarse-grained models can be controlled by varying the magnitude of the three-body interactions. Our findings motivate basis set extensions which separate the many-body contributions of different order.
粗粒化是一种系统地减少用于描述感兴趣系统的自由度的方法。粗粒化可以被认为是对粗粒化自由度的投影，因此取决于用于表示粗粒化力场的基函数的数量和类型。我们表明，粗粒化力场的多体扩展可能导致两体相互作用的实质性变化，从而使它们在短距离处更具吸引力。通过首先参数化两体势能，然后拟合剩余力的附加三体贡献，可以缓解这种相互作用。该方法在液水中得到了说明，其中三体相互作用对于再现结构性质至关重要，而在甲醇液体中，两体相互作用足以再现原子系统的主要结构特征。此外，我们证明可以通过改变三体相互作用的大小来控制粗粒化模型的结构和热力学精度。我们的发现促使扩展基组，从而将不同阶的多体贡献分开。
