Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
Physics Department, University of Trento, Via Sommarive, 14, I-38123 Trento, Italy.
J Chem Phys. 2019 Oct 14;151(14):144105. doi: 10.1063/1.5117780.
By analogy with single-molecule pulling experiments, we present a computational framework to obtain free energy differences between complex solvation states. To illustrate our approach, we focus on the calculation of solvation free energies (SFEs). However, the method can be readily extended to cases involving more complex solutes and solvation conditions as well as to the calculation of binding free energies. The main idea is to drag the solute across the simulation box where atomistic and ideal gas representations of the solvent coexist at constant temperature and chemical potential. At finite pulling speeds, the resulting work allows one to extract SFEs via nonequilibrium relations, whereas at infinitely slow pulling speeds, this process becomes equivalent to the thermodynamic integration method. Results for small molecules well agree with literature data and pave the way to systematic studies of arbitrarily large and complex molecules.
通过类比单分子拉伸实验，我们提出了一种计算框架来获得复杂溶剂化状态之间的自由能差异。为了说明我们的方法，我们专注于溶剂化自由能（SFE）的计算。然而，该方法可以很容易地扩展到涉及更复杂的溶质和溶剂化条件以及结合自由能的计算。主要思想是将溶质拖过模拟盒，在该模拟盒中，溶剂的原子和理想气体表示在恒定的温度和化学势下共存。在有限的拉伸速度下，由此产生的功允许通过非平衡关系提取 SFE，而在无限缓慢的拉伸速度下，此过程等效于热力学积分法。小分子的结果与文献数据很好地吻合，为系统地研究任意大而复杂的分子铺平了道路。
