Kwon Youngjun, Eun Changsun
Department of Chemistry, Hankuk University of Foreign Studies, Yongin 17035, Republic of Korea.
Phys Chem Chem Phys. 2023 Mar 1;25(9):7032-7046. doi: 10.1039/d2cp04666k.
In this work, we investigated the free energy barrier for transporting water molecules from one place to another. To properly address this issue, we considered a simple model system in which two separate compartments were connected a subnanometer channel; all water molecules were initially in one compartment, and the other compartment was empty. Using umbrella sampling in molecular dynamics simulations, we calculated the free energy change for transporting all water molecules to the initially empty compartment. The free energy profile clearly indicated the presence of a free energy barrier, and the magnitude and shape of the barrier were dependent on the number of water molecules to be transported. To better understand the nature of the profile, we performed additional analyses on the potential energy of the system and hydrogen bonding between water molecules. Our study sheds light on a method for calculating the free energy of a transport system as well as the fundamental aspects of water transport.
在这项工作中，我们研究了水分子从一个地方传输到另一个地方的自由能垒。为了恰当地解决这个问题，我们考虑了一个简单的模型系统，其中两个独立的隔室通过一个亚纳米通道相连；所有水分子最初都在一个隔室中，另一个隔室是空的。利用分子动力学模拟中的伞形抽样，我们计算了将所有水分子传输到最初为空的隔室的自由能变化。自由能剖面图清楚地表明存在自由能垒，并且该垒的大小和形状取决于要传输的水分子数量。为了更好地理解该剖面图的性质，我们对系统的势能和水分子之间的氢键进行了额外的分析。我们的研究揭示了一种计算传输系统自由能的方法以及水传输的基本方面。
