Pedroza Luana S, Brandimarte Pedro, Rocha Alexandre Reily, Fernández-Serra M-V
ICTP South American Institute for Fundamental Research , Instituto de Física Teórica , Universidade Estadual Paulista , São Paulo SP 01140-070 , Brazil . Email:
Centro de Ciências Naturais e Humanas , Universidade Federal do ABC , Santo André , São Paulo , Brazil 09210-170.
Chem Sci. 2017 Oct 11;9(1):62-69. doi: 10.1039/c7sc02208e. eCollection 2018 Jan 7.
Understanding the local structure of water at the interfaces of metallic electrodes is a key issue in aqueous-based electrochemistry. Nevertheless a realistic simulation of such a setup is challenging, particularly when the electrodes are maintained at different potentials. To correctly compute the effect of an external bias potential applied to truly semi-infinite surfaces, we combine Density Functional Theory (DFT) and Non-Equilibrium Green's Function (NEGF) methods. This framework allows for the out-of-equilibrium calculation of forces and dynamics, and directly correlates to the chemical potential of the electrodes, which is introduced experimentally. In this work, we apply this methodology to study the electronic properties and atomic forces of a water molecule at the interface of a gold surface. We find that the water molecule tends to align its dipole moment with the electric field, and it is either repelled or attracted to the metal depending on the sign and magnitude of the applied bias, in an asymmetric fashion.
理解金属电极界面处水的局部结构是水基电化学中的一个关键问题。然而，对这种设置进行实际模拟具有挑战性，特别是当电极保持在不同电位时。为了正确计算施加到真正半无限表面的外部偏置电位的影响，我们结合了密度泛函理论（DFT）和非平衡格林函数（NEGF）方法。该框架允许进行力和动力学的非平衡计算，并直接与通过实验引入的电极化学势相关。在这项工作中，我们应用这种方法来研究金表面界面处水分子的电子性质和原子力。我们发现，水分子倾向于使其偶极矩与电场对齐，并且根据所施加偏置的符号和大小，以不对称的方式被金属排斥或吸引。
