Bonding Character and Formation Energy of Point Defects of He and Vacancy on (001) Surface of bcc Iron by First Principle Calculations  

作　　者：Jun CAI Daogang LU 

机构地区：[1]School of Nuclear Science and Engineering, North China Electric Power University

出　　处：《Acta Metallurgica Sinica(English Letters)》2013年第1期25-32,共8页金属学报（英文版）

基　　金：supported by National Basic Research Program of China (No.2007CB209803);the National Natural Science Foundation of China (No.51231002);the Applied Basic Research Program from Hebei Province

摘　　要：The structure and energy of He impurities and vacancy on （001） surface of bcc iron are investigated by an ab initio method. Three cases for stabilities of a He atom at the surface are found： some of He atoms at surface atomic layers （SAL） relax into vacuum gap; some of surface He atoms at octahedral interstitial site relax into more stable tetrahedral interstitial site; some of surface He atoms still stay at tetrahedral interstitial site. The un-stability of the He atom at the surface system can be explained by deformation mechanism of charge densities and electronic densities of states. It is found that formation energy of the point defects from the topmost SAL to bulk-like atomic layer increase gradually, for example, the formation energies of a monovacancy at the first five topmost SALs are equal to 0.33, 1.56, 2.04, 2.02 and 2.11 eV, respectively. The magnetic moments of Fe atoms in the surface atomic layers are also calculated.The structure and energy of He impurities and vacancy on （001） surface of bcc iron are investigated by an ab initio method. Three cases for stabilities of a He atom at the surface are found： some of He atoms at surface atomic layers （SAL） relax into vacuum gap; some of surface He atoms at octahedral interstitial site relax into more stable tetrahedral interstitial site; some of surface He atoms still stay at tetrahedral interstitial site. The un-stability of the He atom at the surface system can be explained by deformation mechanism of charge densities and electronic densities of states. It is found that formation energy of the point defects from the topmost SAL to bulk-like atomic layer increase gradually, for example, the formation energies of a monovacancy at the first five topmost SALs are equal to 0.33, 1.56, 2.04, 2.02 and 2.11 eV, respectively. The magnetic moments of Fe atoms in the surface atomic layers are also calculated.

关 键 词：ab initio calculations Single point defects bcc Fe （001） surface ELECTRONICSTRUCTURE 

分 类 号：TG141[一般工业技术—材料科学与工程]