新型苯并呋喃噻吩(吲哚)二酮染料的密度泛函理论研究

在密度泛函理论(DFT)的B3LYP/6-31G*水平上对8个苯并呋喃噻吩(吲哚)二酮染料进行理论计算,分析了CH3、OCH3、Br对染料母体的几何结构、稳定性和能量的影响。并应用含时的密度泛函理论(TD-DFT)在同样水平下计算它们的电子光谱。结果发现:母体被取代后能量降低,结构变稳定;8个苯并呋喃噻吩(吲哚)二酮染料的最低单重激发态均主要源自HOMO-LOMO(π-π*)跃迁。     

靛蓝及其取代物的密度泛函理论研究

运用量子化学中密度泛函理论(DFT)方法，在B3LYP／6-31G^ 水平上对靛蓝及其芳环4，4′-，5，5′-，6，6′-，7，7′-取代衍生物进行理论计算．探讨了F，Cl，Br，NO2，CH3O，CH3在不同位置的取代对分子的几何构型、电子结构和电子光谱的影响，获得与实验结果相一致的结论．还用含时密度泛函理论(TD-DFT)方法在相同水平计算其电子光谱．结果表明靛蓝及其芳环取代衍生物的最低激发单重态(S1)均源自HOMO-LUMO(π-π^*)跃迁．     

蒽醌及其羟基衍生物的密度泛函理论研究

运用密度泛函理论, 在B3LYP/6-31G*水平上, 对蒽醌及其羟基取代衍生物进行理论计算. 几何全优化的结果表明, 标题化合物均取平面构型, 分子内氢键对几何构型和电子结构影响很大. 基于简谐振动分析求得IR谱频率和强度, 并作了对称性分类和指认, 计算值与实验值良好相符. 运用含时密度泛函理论方法在相同水平上计算了标题物的电子吸收光谱, 发现蒽醌芳环取代衍生物的最低激发单重态均源自HOMO-LUMO(π→π*)跃迁. 基于振动分析, 由统计热力学求得了标题物的热力学性质.     

取代基对依布硒啉电子结构及光谱性质影响的理论研究

采用密度泛函理论B3LYP方法在6-311++G**水平对依布硒啉及其6个衍生物进行结构优化,并分析了取代基对分子几何构型、电荷分布、前线轨道能级分布的影响.在相同计算水平上采用含时密度泛函理论方法进行了电子光谱研究,讨论了取代基对电子光谱的影响.计算结果表明,标题化合物分子为非平面结构,苯并异硒唑酮环与苯环之间存在一...     

高性能D-π-A型三芳胺类光敏染料的理论设计和表征

基于密度泛函理论(DFT)以及含时密度泛函理论(TDDFT)计算,系统研究了具有不同π桥(环戊联噻吩T和二萘嵌苯P)和受体(氰基丙烯酸CA、苯并噻二唑-苯甲酸BTBA和乙炔基苯并噻二唑-苯甲酸EBTBA)的6个D-π-A芳胺类染料分子的几何和电子结构、吸收光谱、电子注入寿命、染料吸附后导带能级的移动以及电子复合速率等性质.计算结果表明,除TPA-P-BTBA分子外,其余分子均展现出可以与TPA-T-CA(C218)相媲美甚至超越的光捕获能力;所有染料的电子注入寿命均在飞秒(fs)尺度上,展现出超快的电子注入速率;染料吸附之后所引起的TiO_2半导体导带能级移动均为0.25 eV左右,有利于开路电压(V_OC)的提高.重要的是,对于电子复合速率,TPA-T-CA约是TPA-T-EBTBA和TPA-P-EBTBA的44倍,是TPA-T-BTBA的11倍,因此推测,TPA-P-EBTBA、TPA-T-EBTBA以及TPA-T-BTBA将具有更高的短路电流、开路电压和效率,将成为染料敏化太阳能电池(DSSC)领域中具有很大潜力的优秀光敏剂替代者     

二聚(2,5-噻吩乙烯撑)基态和激发态的电子结构: 桥基和芳环取代的影响

采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)方法, 在B3LYP/TZVP水平下, 研究了一系列给电子基团(—NH2, —OCH3和—CH3)和吸电子基团(—CCH, —CN和—NO2)在二聚(2,5-噻吩乙烯撑)(2TV)的桥基和芳环上取代对基态和激发态电子结构的影响. 结果表明, 取代基的给/吸电子能力和取代位置对衍生物的几何结构以及吸收发射光谱均有重要影响, 其中氨基(—NH2)和硝基(—NO2)取代对2TV电子结构的影响较为显著. 此外, 对于桥基和芳环取代, 随着取代基吸电子能力的增强, 衍生物的前线分子轨道HOMO和LUMO的能级均呈逐渐降低的趋势.     

邻二氮杂苯-水复合物的氢键结构与性质

用密度泛函理论B3LYP方法和MP2方法对邻二氮杂苯-水复合物基态的氢键结构与相互作用能进行了理论计算,结果表明复合物之间存在较强的氢键N…H－O.在复合物中,水的H－O对称伸缩振动频率明显红移.同时,使用含时密度泛函理论方法计算了邻二氮杂苯单体及复合物的低占据1(n,π*) 和1(π,π*) 态的垂直激发能,计算结果与实验值吻合较好.     

1,2,4-三氮杂苯-(H2O)n复合物氢键相互作用的密度泛函理论研究

用密度泛函理论方法在B3LYP／6—31 G**水平上对1，2，4-三氮杂苯-(H2O)n(n=1，2，3)氢键复合物的基态进行了结构优化和能量计算，结果表明复合物之间存在较强的氢键作用，所有稳定复合物结构中形成一个N…H--O氢键并终止于弱O…H—C氢键的氢键水链的构型最稳定．同时，用含时密度泛函理论方法(TD—DPT)在TD—B3LYP／6—31 G**水平上计算了1,2，4-三氮杂苯单体及其氢键复合物的单重态第-1(n，π*)垂直激发能．     

有机染料敏化剂JK16和JK17的几何结构、电子结构及相关性质

运用密度泛函理论中的杂化泛函B3LYP研究了高效太阳能电池新型染料敏化剂JK16和JK17的几何结构、电子结构、极化率和超极化率, 并用含时密度泛函理论(TDDFT)研究了电子吸收谱. 基于含时密度泛函理论计算结果和实验结果的定性符合, 指认了在可见和近紫外区的吸收属于π→π*跃迁. 计算结果还表明JK16和JK17激发能最低的三个跃迁都与光诱导电荷转移过程有关, 而且二-二甲基芴氨基苯并噻吩基团对光电转换过程的敏化起主要作用, 发生于染料敏化剂JK16、JK17和TiO2界面之间的电荷转移是由染料分子激发态向半导体导带的电子注入过程. 此外, 通过对JK16和JK17的比较, 分析了亚乙烯基对几何结构、电子结构和谱学特性的影响.     

新型四硫富瓦烯-三苯胺类光敏染料理论研究（英文）

在简单结构的D-π-A三苯胺光敏染料(YD1)中引入不同数量的四硫富瓦烯(TTF)单元作为次级电子给体以增强有机光敏染料的给电子能力,设计了两个结构分别为D-D-π-A(YD2)以及2D-D-π-A(YD3)的光敏染料分子,并且采用密度泛函理论(DFT)和含时密度泛函理论(TD-DFT)分别模拟计算了纯光敏剂分子及其吸附二氧化钛团簇后的几何构型、电子结构以及光物理性能。采用周期性密度泛函理论模拟计算光敏染料分子在二氧化钛(101)面吸附的表面形貌以及态密度(DOS)。计算结果表明,TTF单元的引入不仅可以有效减少光敏染料分子的团聚,还可以提升其吸收性能。此外,光吸收效率(LHE)、电子注入驱动力(ΔG~(inject))以及DOS的计算结果显示,YD2和YD3理论上可以呈现出比YD1更高的短路电流密度(J_(sc))以及开路电压(V_(oc))。因此,通过本文的理论研究表明,TTF单元可以作为有机光敏染料中的次级电子给体来改善光敏染料的性能。     

虚轨道定域化

通过引入虚轨道定域化函数，扩展了集居数的定域化方法，在从头算STO－3G水平上用护展后的方法计算无机小分子、烷烃、卤代烷、醇、胺及共轭烃等，结果表明，定域占据轨道与定域虚轨道的系数和能级分布相似的规律。     

六氢吡啶和氨形成的氢键团簇C5H10NH(NH3)n(n=1～3)结构的从头算研究

在RHF/6-31G(d)水平下,对C5H10NH(NH3)n(n=1～3)氢键团簇的平衡构型进行了从头算研究,优化得到各种可能的平衡构型.C5H10NH(NH3)为线型氢键结构,而C5H10NH(NH3)2为三元环结构,C5H10NH(NH3)3为四元环结构.在MP2/6-31G(d)//B3LYP/6-31G(d)水平下,对最稳定构型C5H10NH(NH3)n(Ⅰ)(n=1～3)的分子轨道进行布居分析,并且对相应的占据轨道进行指认.C5H10NH(NH3)n(Ⅰ)(n=1～3)垂直电离势的计算结果表明,形成氢键团簇后,分子的垂直电离势降低.     

Calculations of the optical spectra of hydrocarbon radical cations based on Koopmans' theorem

The first few bands in the optical spectra of radical cations can often be interpreted in terms of A-type transitions that involve electron promotions from doubly occupied to the singly occupied molecular orbital (SOMO) and/or B-type transition which involve electron promotion from the SOMO to virtual molecular orbitals. We had previously demonstrated that, by making use of Koopmans' theorem, the energies of A-type transitions can be related to orbital energy differences between lower occupied MOs and the highest occupied MO (HOMO) in the neutral molecule, calculated at the geometry of the radical cation. We now propose that the energies of B-type transitions can be related similarly to energy differences between the lowest unoccupied MO (LUMO) and higher virtual MOs in the dication, also calculated at the geometry of the radical cation, by way of an extension of Koopmans' theorem to virtual MOs similar to that used sometimes to model resonances in electron scattering experiments. The optical spectra of the radical cations of several polyenes and aromatic compounds, the matrix spectra of which are known (or presented here for the first time), and for which CASSCF/CASPT2 calculations are available, are discussed in terms of these Koopmans-based models. Then the spectra of five poly(bicycloalkyl)-protected systems and that of hexabenzocoronene, compounds not amenable to higher level calculations, are examined and it is found that the Koopmans-type calculations allow a satisfactory interpretation of most of the features in these spectra. These simple calculations therefore provide a computationally inexpensive yet effective way to assign optical transitions in radical ions. Limitations of the model are discussed.     

Empty level structure and dissociative electron attachment cross section in (bromoalkyl)benzenes

The gas-phase electron transmission (ET) and dissociative electron attachment (DEA) spectra are reported for the series of (bromoalkyl)benzenes C6H5(CH2)nBr (n = 0-3), where the bromine atom is directly bonded to a benzene ring or separated from it by 1-3 CH2 groups, and the dihalo derivative 1-Br-4-Cl-benzene. The relative DEA cross sections (essentially due to the Br- fragment) are reported, and the absolute cross sections are also evaluated. HF/6-31G and B3LYP/6-31G* calculations are employed to evaluate the virtual orbital energies (VOEs) for the optimized geometries of the neutral state molecules. The pi* VOEs, scaled with empirical equations, satisfactorily reproduce the corresponding experimental vertical electron attachment energies (VAEs). According to the calculated localization properties, the LUMO (as well as the singly occupied MO of the lowest lying anion state) of C6H5(CH2)3Br is largely localized on both the benzene ring and the C-Br bond, despite only a small pi*/sigma*C-Br interaction and in contrast to the chlorine analogue where the LUMO is predicted to possess essentially ring pi character. This would imply a less important role of intramolecular electron transfer in the bromo derivative for production of the halogen negative fragment through dissociation of the first resonant state. The VAEs calculated as the anion/neutral energy difference with the 6-31+G* basis set which includes diffuse functions are relatively close to the experimental values but do not parallel their sequence. In addition the SOMO of some compounds is not described as a valence MO with large pi* character but as a diffuse sigma* MO.     

簇合物Co6(μ3-E)8(CO)6(E:-S,-Se)的电子结构及相关性能探讨

标题簇合物分子中所含的Co6为八面体结构，这一主干结构从化学上开始合成以来，已历经十余年[1]．由于硫族元素的钻原子簇合物具有如下两方面的作用：它与一些多相钻一硫催化剂的表面结构相当类似，因而可作为其研究模型．另外该簇合物分子可以进行可逆的氧化还原反应且不改变本身结构，依此特性又可作为电子库材料和生物酶电子传递研究的模拟物．所以人们对它的研究兴趣渐趋强烈．大量这些簇合物的合成、结构测定等见诸报道[1－3]．主要的分子类型为Co6（μ3－E）8（PR3）6（E：－S，－Se；R：－Et，－Ph．）．对于它们的研究，详细了…     

Building a bridge between coordination compounds and clusters: bonding analysis of the icosahedral molecules [M(ER)12] (M = Cr, Mo, W; E = Zn, Cd, Hg)

The bonding situation of the icosahedral compounds [M(EH)(12)] (M = Cr, Mo, W; E = Zn, Cd, Hg), which are model systems for the isolated species [Mo(ZnCp*)(3)(ZnMe)(9)] possessing the coordination number 12 at the central atom M, have been analyzed with a variety of charge and energy decomposition methods (AIM, EDA-NOCV, WBI, MO). The results give a coherent picture of the electronic structure and the nature of the interatomic interactions. The compounds [M(EH)(12)] are transition metal complexes that possess 12 M-EH radial bond paths (AIM) that can be described as 6 three-center two-electron bonds (MO). The radial M-EH bonds come from the electron sharing interactions mainly between the singly occupied valence s and d AOs of the central atom M and the singly occupied EH valence orbitals (MO, EDA-NOCV). The orbital interactions provide ~42% of the total attraction, while the electrostatic attraction contributes ~58% to the metal-ligand bonding (EDA-NOCV). There is a weak peripheral E-E bonding in [M(EH)(12)] that explains the unusually high coordination number (MO). The peripheral bonding leads for some compounds [M(EH)(12)] to the emergence of E-E bond paths, while in others it does not (AIM). The relative strength of the radial and peripheral bonding in [Al(13)](-) and [Pt@Pb(12)](2-) is clearly different from the situation in [M(EH)(12)], which supports the assignments of the former species as cluster compounds or inclusion compounds (MO, WBI). The bonding situation in [WAu(12)] is similar to that in [M(EH)(12)].     

四苯硼阴离子电子结构的理论研究

分别应用半经验发子轨道理论的AM1方法和在HF／3－21G水平上的从头算分子轨道法,对四苯硼阴离子的电子结构进行了研究。采用解析梯度技术对四苯硼阴离子的平衡态几何构型进行了全优化,得到了分子轨道、电荷布居、静电势以及红外光谱和紫外光谱等参数,计算结果表明：四苯硼阴离子的静电势分布均匀,其前线轨道能级间隔为12．1398eV,利用组态相互作用法得到的紫外光谱跃迁吸收峰主要位于远紫外区,说明四苯硼离子比较稳定,从头算法得到的红外光谱吸收峰分布与实验结果一致,AM1法得到的红外吸收频率与实验值更接近。     

键能的分子轨道理论研究 1: 理论公式

从LCAO-MO出发, 给出了一个计算键能的近似方法, 即EAB(i)-∑∑CaiSabCbiεi为第i个占据分子轨道(MO)中的一对电子对A-B键键能的贡献。对所有分子轨道求和即为该键的键能: EAB=∑EAB(i)。按该方法, 不仅可以计算各种不同分子中每两个相键连原子间的键能, 还可以从MO及AO角度分析每一具体键, 如σ, π, δ键的键能以及各AO对键能的贡献。该方法虽有别于求键焓和平衡离解能De, 但计算结果和De的实验值甚相符合。通过对键能的分析研究, 能较好地揭示原子间的相互作用关系及化学键的强弱, 从而可进一步探讨化学反应活性, 反应速率等化学性质。     

DFT study of the geometrical and electronic structure of substituted cumulenes in netral and cationic forms

The geometrical and basic energy parameters of monosubstituted cumulenes and their singly and doubly charged cations were calculated by the Hartree-Fock and density functional (DFT) methods at a B3LYP level of theory using the 6-31G(d) basis set. The substituent was fluorine, cyan, amino group, phenyl, cyanophenyl, aminophenyl, or dimethylaminophenyl. In extended linear carbon systems based on cumulene, rotation of a terminal fragment depends on the character of the highest occupied molecular orbital (HOMO) from which electrons are removed. The terminal group rotates through 90 only when the contribution of electron density from the π molecular orbital (MO) of unsubstituted cumulene to the HOMO of substituted cumulene is over 70%. Otherwise, the terminal group rotates through a smaller angle; with a contribution of less than 30%, the dication is planar in any substituted cumulene. Thus quantitative criteria have been determined to evaluate the specific structural effect due to ionization of substituted cumulenes.     

环聚炔苯和环聚炔吡啶组成的盘状液晶中的电荷转移

用电子转移的半经典模型在量子化学B3LYP/6-31G(d)水平(对单体)和B3LYP/STO-3G水平(对二聚物)对环聚炔苯和环聚炔吡啶组成的盘状液晶体系的电荷转移性质进行了研究. 盘状液晶体系的电荷转移速率主要依赖于重组能和电荷转移矩阵元, 重组能越小, 电荷转移矩阵元越大, 则电荷转移速率常数越大. 计算结果表明, 这些大环化合物比目前广泛研究和应用的苯并菲衍生物组成的液晶有较小的重组能, 所以有更好的电荷转移性质. 计算结果对有效地设计和合成高效的光导材料和载流子输送材料是有帮助的.