The structural and electronic properties of monovacancy,divacancy defects within crystalline silicon have been investigated systematically using a new tight-binding model with a 216-atom supercell.The formation energi...The structural and electronic properties of monovacancy,divacancy defects within crystalline silicon have been investigated systematically using a new tight-binding model with a 216-atom supercell.The formation energies and energy levels of all the defect configurations are carefully calculated.The results show that atoms nearer to the defects naturally contribute to gap states more,and are comparable with the experimental values.展开更多
The corrosion of steels in liquid metal lead （Pb） and bismuth （Bi） is a critical challenge in the development of accel-erator driven systems （ADS）. Using a first-principles method with a slab model, we theoretic...The corrosion of steels in liquid metal lead （Pb） and bismuth （Bi） is a critical challenge in the development of accel-erator driven systems （ADS）. Using a first-principles method with a slab model, we theoretically investigate the interaction between the Pb （Bi） atom and the iron （Fe） （100） surface to assess the fundamental corrosion properties. Our investigation demonstrates that both Pb and Bi atoms favorably adsorb on the （100） surface. Such an adsorption decreases the energy required for the dissociation of an Fe atom from the surface, enhancing the dissolution tendency significantly. The seg- regation of six common alloying elements （Cr, A1, Mn, Ni, Nb, and Si） to the surface and their impacts on the corrosion properties are also considered. The present results reveal that Si seems to have a relatively good performance to stabilize the surface and alleviate the dissolving trend caused by Pb and Bi.展开更多
Carbon nanotubes with finite lengths should be natural components of future“nano devices”.Based on orthogonal tight-binding molecular dynamics simulations,we report our study of formation energies,optimal geometrica...Carbon nanotubes with finite lengths should be natural components of future“nano devices”.Based on orthogonal tight-binding molecular dynamics simulations,we report our study of formation energies,optimal geometrical structures and active sites of carbon nanotubes with finite lengths.This should be useful to understand the properties of such natural components.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.69876035,the Fund of Chinese Academy of Sciences and the Fund of University of Science and Technology of China.
文摘The structural and electronic properties of monovacancy,divacancy defects within crystalline silicon have been investigated systematically using a new tight-binding model with a 216-atom supercell.The formation energies and energy levels of all the defect configurations are carefully calculated.The results show that atoms nearer to the defects naturally contribute to gap states more,and are comparable with the experimental values.
基金Project supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.KJCX2-YW-N35 and XDA03010303)the National Natural Science Foundation of China(Grant Nos.91026002 and 91126002)the National Magnetic Confinement Fusion Program,China(Grant No.2011GB108004)
文摘The corrosion of steels in liquid metal lead （Pb） and bismuth （Bi） is a critical challenge in the development of accel-erator driven systems （ADS）. Using a first-principles method with a slab model, we theoretically investigate the interaction between the Pb （Bi） atom and the iron （Fe） （100） surface to assess the fundamental corrosion properties. Our investigation demonstrates that both Pb and Bi atoms favorably adsorb on the （100） surface. Such an adsorption decreases the energy required for the dissociation of an Fe atom from the surface, enhancing the dissolution tendency significantly. The seg- regation of six common alloying elements （Cr, A1, Mn, Ni, Nb, and Si） to the surface and their impacts on the corrosion properties are also considered. The present results reveal that Si seems to have a relatively good performance to stabilize the surface and alleviate the dissolving trend caused by Pb and Bi.
基金Supported in part by Ministry of Education,PRC,the National PAN-DENG Project(95-YU-41)the National Natural Science Foundation of China under Grant No.69876035National High-Tech ICF Committee in China.
文摘Carbon nanotubes with finite lengths should be natural components of future“nano devices”.Based on orthogonal tight-binding molecular dynamics simulations,we report our study of formation energies,optimal geometrical structures and active sites of carbon nanotubes with finite lengths.This should be useful to understand the properties of such natural components.
