H在Mg(0001)表面吸附、解离和扩散的第一性原理研究  

First-Principle Calculations of the Adsorption, Dissociation and Diffusion of Hydrogen on the Mg(0001) Surface

作　　者：吴广新[1] 张捷宇[1] 吴永全[1] 李谦[1] 周国治[1] 包新华[2] 

机构地区：[1]上海大学材料科学与工程学院,上海200072 [2]上海大学理学院,上海200444

出　　处：《物理化学学报》2008年第1期55-60,共6页Acta Physico-Chimica Sinica

基　　金：上海市“登山行动计划”重点基础项目(06JC14031);上海市青年科技启明星计划(06QA14021);全国博士学位论文作者专项资金(200746);上海市科学委员会(05JC14064)资助

摘　　要：采用基于密度泛函的第一性原理方法,同时结合Nudged Elastic Band方法,系统研究了H2分子和H原子在Mg(0001)表面的吸附过程.给出了H2分子的解离路径和势垒,结果表明H2分子的吸附过程中仅存在物理吸附;在给出H原子在Mg(0001)表面的吸附势能面的基础上,进一步研究了H原子在Mg(0001)表面及体内的扩散过程.计算发现,Mg(0001)slab存在表面效应,且对H原子的表面扩散影响较明显.在此基础上,通过比较解离、扩散和放氢环节的激活能数据,为H2分子的解离和氢化物的放氢过程是速控步骤这一结论提供了理论支持.First-principle pseudopotential plane wave calculations and the Nudged Elastic Band method based on the density functional theory （DFT） were used in this article to study the dissociation of molecular hydrogen on a Mg（0001） surface and the subsequent diffusion of atomic hydrogen into the magnesium substrate. First, the dissociation pathway of H2 and the relative barrier were investigated. It was shown that physical adsorption rather than chemisorption of molecular hydrogen was observed in the calculation of the dissociation process of molecular hydrogen. Also, the diffusion process of atomic hydrogen on Mg（0001） was presented. The surface effect, which affected the diffusion of hydrogen obviously, was observed. Finally, comparing the values of the activation energies for the steps of dissociation, diffusion, and desorption, our calculation further showed that the dissociation of H2 and desorption of hydride were the rate-limiting steps.

关 键 词：第一性原理 势能面 吸附能 解离 扩散 

分 类 号：O647.31[理学—物理化学]