论文标题
QM/MD耦合方法，用于建模石墨烯的离子诱导的极化
A QM/MD coupling method to model the ion-induced polarization of graphene
论文作者
论文摘要
我们报告了一种新的量子机械/分子动力学（QM/MD）模拟环，以建模固体/液体界面系统中电子和原子动力学之间的耦合。该方法可以同时描述从接近到电解质的量子机械表面极化率，以及电解质结构和动力学。在当前的设置密度函数紧密结合计算中，用于表面的电子结构计算与经典分子动力学结合以模拟电解质溶液。 QM部分的计算成本降低使与经典的模拟引擎计算可行的耦合，并允许为数百个纳秒的大型系统模拟。我们通过模拟非电荷石墨烯薄片和浸入NACL电解质溶液中的非充电和带电的无限石墨烯纸来测试了该方法。我们发现，当不施加偏差时，离子优先保留在溶液中，并且只有阳离子被轻度吸引到石墨烯的表面。当表面中适中充电并排除任何实质性离子/表面电荷转移时，阳离子与阴离子的优先吸附似乎也持续存在。
We report a new Quantum Mechanical/Molecular Dynamics (QM/MD) simulation loop to model the coupling between the electron and atom dynamics in solid/liquid interfacial systems. The method can describe simultaneously both the quantum mechanical surface polarizability emerging from the proximity to the electrolyte, and the electrolyte structure and dynamics. In the current set up Density Functional Tight Binding calculations for the electronic structure calculations of the surface are coupled with classical molecular dynamics to simulate the electrolyte solution. The reduced computational cost of the QM part makes the coupling with a classical simulation engine computationally feasible and allows simulation of large systems for hundreds of nanoseconds. We tested the method by simulating both a non-charged graphene flake and a non-charged and charged infinite graphene sheet immersed in an NaCl electrolyte solution. We found that, when no bias is applied, ions preferentially remained in solution and only cations are mildly attracted to the surface of the graphene. This preferential adsorption of cations vs anions seems to persist also when the surface is moderately charged and rules out any substantial ions/surface charge transfer.
