3C-SiC材料p型掺杂的第一性原理研究

采用基于第一性原理的密度泛函理论平面波超软赝势法,研究了SiC材料p型掺杂的晶体结构和电子结构性质,得到了优化后体系的结构参数,掺杂形成能,能带结构和电子态密度,计算得到掺杂B,Al,Ga在不同浓度下的禁带宽度.结果表明:随着掺杂B原子浓度的增大,禁带宽度随之减小;而随着掺杂Al,Ga原子浓度的增大,禁带宽度随之增大;在相同浓度下,掺杂Ga的禁带宽度大于掺杂Al,掺Al禁带宽度大于掺B. 关键词： SiC 电子结构 掺杂 第一性原理软件     

双氮协同钴掺杂锐钛矿相二氧化钛电子结构的第一性原理研究

采用基于密度泛函理论的第一性原理计算了双氮原子协同钴原子共掺杂TiO2的几何结构和电子结构. 计算结果发现: 双氮原子掺杂引起的双空穴位与钴原子形成了较强的耦合作用, 并引起晶格结构发生明显变化. 共掺杂的协同效应引起TiO2禁带宽度变窄,在价带顶和导带底出现大量杂质能级, 从而引起吸收带边发生明显红移. 该掺杂方式对调制TiO2禁带宽度有明显的效果, 有望指导后续的实验合成.     

Pt-N共掺杂锐钛矿TiO_2的第一性原理研究

采用基于密度泛函理论(DFT)的第一性原理中的平面波超软赝势(PWPP)方法对理想TiO_2,N单掺杂,Pt单掺杂和Pt-N共掺杂锐钛矿相TiO_2的电子结构进行计算,分析N单掺杂、Pt单掺杂及Pt-N共掺杂对锐钛矿相TiO_2的晶体结构、能带和态密度的影响.计算结果表明:掺杂后TiO_2的晶格发生畸变,原子间键长的变化使晶格发生膨胀,Pt单掺杂、N单掺杂TiO_2禁带宽度变窄,Pt-N共掺杂TiO_2分别在价带顶和导带底产生杂质能级,且禁带宽度缩小范围大,表明Pt-N共掺杂能进一步提高锐钛矿TiO_2催化性能.     

双氮协同钴掺杂锐钛矿相二氧化钛电子结构的第一性原理研究（英文）

采用基于密度泛函理论的第一性原理计算了双氮原子协同钴原子共掺杂TiO_2的几何结构和电子结构.计算结果发现:双氮原子掺杂引起的双空穴位与钴原子形成了较强的耦合作用,并引起晶格结构发生明显变化.共掺杂的协同效应引起TiO_2禁带宽度变窄,在价带顶和导带底出现大量杂质能级,从而引起吸收带边发生明显红移.该掺杂方式对调制TiO_2禁带宽度有明显的效果,有望指导后续的实验合成.     

Pt掺杂CdS光学性质的第一性原理研究

基于密度泛函理论的第一性原理平面波超软赝势方法,运用Castep计算分析了Pt元素掺杂CdS结构,对本征CdS和掺杂晶体的能带结构、态密度以及光学性质进行了分析对比, 由掺杂前后的结果分析发现：Pt掺杂闪锌矿相CdS产生了新的能带,带隙明显缩小;CdS的吸收边产生红移,禁带宽度变窄,在可见光区具有较大吸收系数,提高了可见光的利用率,表现出较好的可见光光催化活性。     

Pt掺杂CdS光学性质的第一性原理研究

基于密度泛函理论的第一性原理平面波超软赝势方法,运用Castep计算分析了Pt元素掺杂CdS结构,对本征CdS和掺杂晶体的能带结构、态密度以及光学性质进行了分析对比, 由掺杂前后的结果分析发现：Pt掺杂闪锌矿相CdS产生了新的能带,带隙明显缩小;CdS的吸收边产生红移,禁带宽度变窄,在可见光区具有较大吸收系数,提高了可见光的利用率,表现出较好的可见光光催化活性。     

In掺杂ZnO电子结构的第一性原理研究

采用第一性原理平面波超软赝势,计算了纤锌矿ZnO和不同掺杂量下In掺杂ZnO晶体的能带结构、态密度和分波态密度.计算表明,In的掺杂导致ZnO禁带宽度变窄.随着掺杂量的增大,In_xZn_1－xO的导带底和价带顶同时下降,但是导带底比价带顶下降得多,这导致了带隙的变窄.此外,In掺杂使晶胞晶格常数增大,这对带隙的变窄也有一定作用.     

Te掺杂单层MoS2的电子结构与光电性质

采用基于密度泛函理论的第一性原理计算,研究了Te掺杂对单层MoS₂能带结构、电子态密度和光电性质的影响。结果表明,本征单层MoS₂属于直接带隙半导体材料,其禁带宽度为1.64 eV。本征单层MoS₂的价带顶主要由S-3p态电子和Mo-4d态电子构成,而其导带底则主要由Mo-4d态电子和S-3p态电子共同决定;Te掺杂单层MoS₂为间接带隙半导体材料,其禁带宽度为1.47 eV。同时通过Te掺杂,使单层MoS₂的静态介电常数增大,禁带宽度变窄,吸收光谱产生红移,研究结果为单层MoS₂在光电器件方面的应用提供了理论基础。     

W-S共掺杂锐钛矿TiO2第一性原理研究

采用基于密度泛函理论的第一性原理平面波超软赝势法,计算了未掺杂,WS单掺杂及W-S共掺杂TiO2的电子结构和光学性质．结果表明：掺杂后晶格畸变,晶格常数变大并在TiO2禁带中引入杂质能级．对于S单掺杂TiO2,禁带宽度减小和杂质能级的引入导致吸收光谱红移,而对于W单掺杂和W-S共掺杂,禁带宽度的明显增大致使掺杂后TiO2的吸收光谱蓝移．     

锐钛矿TiO2及其掺Fe所导致的红移现象研究：赝势计算和紫外光谱实验

采用平面波超软赝势方法研究了锐钛矿型TiO2及Fe掺杂TiO2的晶体结构和能带结构，计算表明Fe掺杂导致TiO2电子局域能级的出现及禁带变窄，从而导致吸收光谱红移.研究发现，t2g态在红移现象中起了重要作用.紫外透射光谱实验证实了TiO2掺Fe后吸收光谱红移和禁带变窄的理论预言. 关键词： 密度泛函理论 TiO2 Fe掺杂 红移     

First principle study on the electronic structure of fluorine-doped SnO2

The electronic properties of fluorine-doped SnO₂ films were calculated using the plane-wave-based pseudopotential method based on the density functional theory within the local density approximation. The calculated band structure and density of states show that the band gap of SnO₂ narrows due to the presence of the F impurity energy levels in the bottom of the conduction band. The energy of the valence electrons is reduced as the optical absorption edge shifts towards a higher frequency. The charge density and effective masses of carriers of fluorine-doped SnO₂ were also calculated.     

Mn掺杂ZnO光学特性的第一性原理计算

采用基于密度泛函理论(DFT)的第一性原理平面波超软赝势方法计算了纤锌矿ZnO及不同量Mn 掺杂ZnO 晶体的电子结构，分析了掺杂对ZnO 晶体的能带结构、电子态密度、差分电荷分布的影响. 计算结果表明，随着Mn 掺杂含量的增加，ZnO 禁带宽度相应增加并且对紫外吸收区的光吸收能力也随之增强.     

Mn掺杂ZnO光学特性的第一性原理计算

采用基于密度泛函理论(DFT)的第一性原理平面波超软赝势方法计算了纤锌矿ZnO及不同量Mn 掺杂ZnO 晶体的电子结构,分析了掺杂对ZnO 晶体的能带结构、电子态密度、差分电荷分布的影响. 计算结果表明,随着Mn 掺杂含量的增加,ZnO 禁带宽度相应增加并且对紫外吸收区的光吸收能力也随之增强. 关键词： 密度泛函理论(DFT) 第一性原理 超软赝势 Mn掺杂ZnO     

Structural,electronic, optical and bonding properties of strontianite,SrCO3: First-principles calculations

The first-principles calculations are performed within the density functional theory to investigate the crystal structure, energy band structure, density of states, optical properties, and bonding properties of strontianite. The optimized structure parameters and bonding results with the generalized gradient approximation (GGA) functional and the localized density approximation (LDA) functional are in good agreement with the earlier experimental data. The band structure, density of states and chemical bonding of strontianite have been calculated and analyzed. The indirect band gap of strontianite is estimated to be ~4.45 eV (GGA) or ~4.24 eV (LDA). The absorption, reflectivity, refractive index and extinction coefficient have been calculated using the imaginary part of the dielectric function. The calculated results of the optical properties show that strontianite has an optical anisotropy along [100] (or [010]) and [010] polarization directions of incoming light. Furthermore, the calculated results of the density of states and Mulliken population indicate that the interactions among atoms are both ionic and covalent bonding in strontianite.     

Density of states of Nb and Mo using Slater-Koster interpolation

Slater-Koster parameters are given which have been fit to APW band calculations for Nb and Mo. The density of states at the Fermi surface of the 4d bcc alloys agrees well with a rigid band interpretation of the calculated density of states.     

0.5NdAlO3-0.5CaTiO3电子结构及光学性质的第一性原理计算

采用基于第一性原理密度泛函理论的平面波赝势方法,对0.5NdAlO₃-0.5CaTiO₃晶体进行结构优化,并对其能带结构,态密度和光学性质进行了理论计算.结构优化后晶格参数与实验数据相符合,误差小于1%;能带计算结果表明0.5NdAlO₃-0.5CaTiO₃为间接带隙,带隙值为0.52eV;费米面附近的能带由Nd-4f,O-2p,Nd-4p,Al-3p,Ti-4d层的电子态密度确定.同时也计算了该结构的介电函数,反射率和复折射率等光学性质.     

The XPS valence band of nickel metal

The XPS valence band spectrum of evaporated nickel is compared with a theoretical density of states curve and with a synthetic density of states curve obtained by adding two XPS valence band spectra of copper shifted by 0.3eV with respect to each other. Both calculated curves agree with the main features of the XPS valence band spectrum.     

Calculation of dipole moment functions with density functional theory: application to vibrational band intensities

We have calculated fundamental and overtone XH stretching vibrational band intensities for H₂O, benzene, cyclohexane, 1,3-butadiene, and HCN. The band intensities were calculated with a simple harmonically coupled anharmonic oscillator local mode model and a series expanded dipole moment function. The dipole moment functions were obtained from local, non-local and hybrid density functional theory calculations with basis sets ranging from 6–31G(d) to 6–311++G(3df,3pd). The calculated band intensities have been compared with intensities calculated with conventional ab initio methods and with experimental results. Compared with conventional correlated ab initio methods, a carefully chosen density functional method and basis set seems to give better fundamental and overtone intensities with far less resources used. We have found that the density functional methods appear to be less sensitive to the choice of basis set, with little difference between the results obtained with a non-local or hybrid density functional method.     

Effect of oxidation of graphene nanoribbons on electronic and magnetic properties

The electronic properties, band gap and ionization potential as well as the energies of the singlet and triplet states of zigzag and armchair graphene nanoribbons are calculated as a function of the number of oxygen atoms on the ribbon employing density functional theory at B3LYP/6-31G* level. The calculated band gaps indicate that both structures are semiconducting. The band gap of the armchair ribbons initially decreases followed by an increase with oxygen number. For zigzag ribbons the band gap decreases with increasing oxygen number whereas the ionization potential increases with oxygen content. In both armchair and zigzag ribbons the ionization potential shows a gradual increase with the number of oxygen atoms. Some of the oxygenated ribbons calculated have triplet ground states and have the density of states at the Fermi level for spin down greater than spin up suggesting the possibility they may be ferromagnetic semiconductors.