论文部分内容阅读
取Li_7H和Li_9H两个原子簇模拟氢原子与含台阶的金属锂表面的相互作用,以小基组用abinitio方法计算了体系的吸附和表面扩散势能面(或势能曲线),结果表明:(1)对Li_7H体系,台阶面附近沿垂直于边棱方向存在三种不同的桥位吸附位,最稳定的吸附位在上台面接近台阶边棱处,台阶面显著地改变了表面扩散活化能,台阶边棱处有一个较高的势垒,于是,迁移原子将会在台阶边棱处受到反射,并可被捕获于台阶面上及其附近,由势能面确定了最低能量表面扩散途径,(2)对Li_9H体系,在Li_7H原子簇基础上增加次表面层两个锂原子后,表面扩散活化能略有减小,氢原子在上台面的桥位吸附更趋稳定,各吸附位相对稳定性及势垒几何位置几无改变,这些结果显示了台阶面对氢原子的化学吸附和表面扩散发生扰动,台阶边棱对表面扩散起着重要作用。
The interaction between hydrogen atoms and stepped lithium metal surfaces was simulated by using two atomic clusters Li_7H and Li_9H. The adsorption and surface potential energy potential curves (or potential energy curves) of the system were calculated by abinitio method. The results showed that: (1 ) Li_7H system, there are three different adsorption sites along the vertical direction to the edge. The most stable adsorption sites are located near the step edge on the upper stage. The step surface significantly changes the surface diffusion activation energy. The step There is a higher barrier at the edge, so the migrating atoms will be reflected at the step edges and may be captured on and near the step surface, and the lowest energy surface diffusion path is determined by the potential energy surface. (2 ) On the Li_9H system, the activation energy of surface diffusion slightly decreases after the addition of two lithium atoms on the surface of Li_7H clusters, and the hydrogen adsorption on the upper surface of the bridge more stable, the relative stability of each adsorption site and The geometric positions of the barriers are almost unchanged. These results show that the steps face the chemical adsorption and surface diffusion of hydrogen atoms, and the stepped edges play an important role in the surface diffusion.