第一性原理方法探讨氮气在UO_2(111)表面的吸附行为  

First-principles Study of Nitrogen Adsorption on UO_2(111)Surface

作　　者：聂锦兰[1] 敖蕾[1] 刘柯钊[2] 黄河[2] 

机构地区：[1]电子科技大学物理电子学院,成都610054 [2]表面物理与化学重点实验室,绵阳621907

出　　处：《材料导报》2015年第20期140-143,共4页Materials Reports

基　　金：国家自然科学基金(51201026);中央高校基本科研业务费专项资金(ZYGX2011J038)

摘　　要：采用第一性原理计算模拟方法对氮气分子及原子在UO2(111)表面的吸附行为进行了系统的研究。计算结果表明,N2在UO2(111)表面倾向于以分子吸附的形式存在,其最稳定的吸附构型为分子中心位于氧原子顶部或三重洞位的情形。两种构型下的N-N键的两端均指向相邻的另外两个高对称吸附位置。对于氮原子的表面吸附,发现其位于第二子层的铀原子的上方时最为稳定,吸附能为-4.792eV,为较强的化学吸附。而对次表面吸附的考察发现,氮原子嵌入最外氧原子层时的稳定性高于表面上吸附的情形。态密度分析表明,对于氮原子吸附,N 2p与U 5f电子态在费米能级附近有非常明显的轨道杂化,表明氮原子主要与铀原子发生了化学作用,N-U键存在共价成分。First-principles calculations have been performed to study the adsorption of molecular and atomic nitrogen on UO2（111）surface.The results have shown that N2 prefers the molecular adsorption on UO2（111）surface,centering on top of O or hollow sites,with the N-N bond pointing to another two adjacent high-symmetry sites.For atomic N adsorption,the occupation on top of the second layer U atom（hcp site）was found to be the most stable configuration,with the adsorption energy of-4.792 eV,indicating a strong chemical adsorption.The investigation of the sub-surface adsorption revealed that the incorporation of N into the top O layer was more stable than those surface adsorption configurations.The analysis on the density of states turned out that the strong orbital hybridization between N 2p and U 5fstates near the Fermi level exists for atomic adsorption.These indicated that the chemical interaction between N and U dominated the adsorption of N on UO2（111）,forming a N-U bond with covalent component.

关 键 词：第一性原理 二氧化铀 腐蚀防护 表面吸附 

分 类 号：O469[理学—凝聚态物理]