Development of New Method Based on the Density Functional Theory and Application to Nonequilibrium Electronic Processes

基于密度泛函理论的新方法的发展及其在非平衡电子过程中的应用

• 批准号: 15607018
• 负责人: WATANABE Kazuyuki
• 金额: $ 1.34万
• 依托单位: TOKYO UNIVERSITY OF SCIENCE
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2003
• 资助国家: 日本
• 起止时间: 2003 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-15607018/
• 关键词: Partitioned Real-Space Density-Functional Method; Time-Dependent Density-Functional Method; Capacitance; Nonequilibrium Electronic Processes; Carbon Nanostructures; 炭素ナノ構造

The calculation results on nonequilibrium electronic processes by the partitioned real-space density functional(PRDF) method and time-dependent density functional theory(TDDFT) method are summarized..1.[Capacitance of Nano-Scale Structures by the PRDF](1)Capacitances of two nano-scale electrodes of a cyclopentene molecule, fullerene, carbon nanotube and spherical jellium with 〜1nm space gap are found to be 〜10^<-20>F and the values are close to the experimental ones.(2)Self-capacitances of linear carbon chains Cn, fullerenes encapsulating carbon clusters and spherical jelliums are calculated. The self-capacitance significantly depends on the number of carbon atoms n of Cn and carbon cluster in C_<60>, which is a quantum effect of capacitance at nano-scale. We also found that the electronic-states origin of electron-number dependent capacitance of spherical jellium is the discrete electronic-levels.2.[Field Emission Mechanisms of Carbon Nanostructures and Photoabsorption Spectra of Arom … More atic Molecules by the TDDFT](1)Field emission(FE) currents of diamond surface is more significant from hydrogenated surface than clean surface due to the low ionization energy caused by adsorbed hydrogen. We found that the hydrogen complex defects in the subsurface enhance the emission current because the defect level that is responsible for FE is generated in the energy-band gap.(2)FE of graphitic ribbons are investigated. The dangling-bond(DB) states are found to be a main source for FE and π state or edge state do not contribute to FE. This property is independent of the direction of applied electric field, although the emission current is much larger for a parallel field along the graphitic sheet than a perpendicular field. We further found that the FE current increases dramatically from atomic vacancy defects of graphite sheet because the DB states are generated in the atomic vacancies.(3)The photoabsorption spectra of linear aromatic molecules are investigated by the real-time TDDFT and linear response theory combined with TDDFT. The real-time TDDFT scheme provides more reliable results on photoabsorption cross section and oscillator strength in the higher energy regime than linear-response scheme. The most prominent peak in the spectra is attributed to the electronic excitation in the whole region of the molecule. Less

总结了用分块实空间密度泛函（PRDF）方法和含时密度泛函理论（TDDFT）方法对非平衡电子过程的计算结果. 1.（1）环戊烯分子、富勒烯、碳纳米管和球形凝胶的两个纳米级电极的电容被发现为10 μ <-20>F，并且该值与实验值接近。（2）计算了线型碳链Cn、包裹碳团簇的富勒烯和球形凝胶的自电容。自电容的大小主要取决于Cn中碳原子数n和C_2中碳原子团簇的数目，<60>这是纳米尺度下电容的量子效应。我们还发现，电子数依赖的球形凝胶电容的电子态起源是离散的电子能级。[碳纳米结构的场发射机制和芳香族化合物的光吸收光谱 ...更多信息 （1）金刚石表面的场发射（FE）电流在氢化金刚石表面比清洁金刚石表面更显著，这是由于吸附的氢导致的电离能较低。我们发现，在次表面的氢复合物缺陷增强的发射电流，因为负责FE的缺陷级中产生的能带隙。(2)FE的石墨带进行了研究。结果表明，悬挂键态是场效应的主要来源，而π态和边缘态对场效应没有贡献.这种特性与所施加的电场的方向无关，尽管对于沿石墨片沿着的平行场，发射电流比垂直场大得多。我们进一步发现，FE电流从石墨片的原子空位缺陷中急剧增加，因为DB态产生于原子空位中。（3）用实时TDDFT和线性响应理论结合TDDFT研究了线性芳香分子的光吸收光谱。实时TDDFT方案提供了更可靠的结果光吸收截面和振子强度在更高的能量范围比线性响应方案。光谱中最突出的峰归因于分子整个区域中的电子激发。少

项目成果

Ab initio study of field emission from hydrogen defects in diamond subsurfaces

金刚石次表面氢缺陷场发射的从头算研究

• 发表时间: 2004
• 期刊: Applied Surface Science 237
• 作者: M.Araidai;K.Watanabe
• 通讯作者: K.Watanabe

Ab Initio Calculation of Capacitance of Nanostructures

纳米结构电容的从头算

• 发表时间: 2005
• 期刊: Japanese Journal of Applied Physics (掲載許可)
• 作者: K.Watanabe;S.Watanabe;M.Tanaka;N.Nakaoka
• 通讯作者: N.Nakaoka

Ab-initio calculation of field emission (in Japanese)

场发射的从头计算（日语）

• 发表时间: 2003
• 期刊: Solid State Physics 38
• 作者: S.Watanabe;Y.Gohda;K.Watanabe;K.Tada;M.Araidai
• 通讯作者: M.Araidai

電界放射の第一原理計算

场辐射的第一性原理计算

• 发表时间: 2003
• 期刊: 固体物理 38
• 作者: 渡邉聡;合田義弘;渡辺一之;多田和広;洗平昌晃
• 通讯作者: 洗平昌晃

ナノ物性計測シミュレータの開発に向けて

致力于开发纳米​​物理特性测量模拟器

• 发表时间: 2003
• 期刊: 化学工業 54
• 作者: 渡邉聡;渡辺一之
• 通讯作者: 渡辺一之