Surface diffusion is an interesting and practically important phenomenon in many areas of chemistry and physics. One emerging problem is that of Li wetting on high-Z plasma-facing metals, especially tungsten, for application in tokamak reactors. We report construction of a Li-W binary force field to describe the interface between liquid Li and solid W. We show that this force field can simulate well the atomic processes of liquid Li diffusing across the W surface, as compared with results from first-principles calculations. We find that Li atoms have different wetting behaviors on different surfaces of W. Diffusion is the fastest on the (110) surface and the slowest on the (100) surface. Diffusion of second Li layer on the (110) surface is activated at relatively low temperatures above 262 K. In addition, the diffusion rate of single-layer Li changes with the coverage rate of Li on (110) surface. High diffusion coefficients at coverage rate of $\theta$ = 1/6, 1/3 and 1 are found to be related to the 2D phase transition of Li on the (110) surface.

在化学和物理学的许多领域中，表面扩散是一个有趣的且实际上是重要的现象。一个新兴的问题是锂在用于托卡马克反应堆的高Z等离子体金属（尤其是钨）上的润湿。我们报告了一个Li-W二元力场的构造来描述液态Li和固体W之间的界面。我们证明，与第一批实验结果相比，该力场可以很好地模拟液态Li扩散穿过W表面的原子过程。原理计算。我们发现Li原子在W的不同表面上具有不同的润湿行为。扩散在（110）表面上最快，而在（100）表面上最慢。第二锂层在（110）表面上的扩散在262 K以上的相对较低的温度下被激活。此外，单层Li的扩散速率随（110）表面Li的覆盖率而变化。高扩散系数，覆盖率为$\theta$ 发现1 / 6、1 / 3和1与（110）表面上Li的2D相变有关。