C2v对称性簇Ru2N2的理论计算

采用密度泛函(B3LYP)方法计算了Ru2的部分低能电子组态，得到Ru2基态的电子谱项为7Δu，平衡核间距re=0.228 nm，振动频率ωe=338 cm－1，离解能De=1.92 eV. 同时计算了具有C2v对称性的Ru2N2簇中氮的活化情况，得到了各个优化几何构型下的键参数和体系能量.计算结果表明，氮氮键的活化程度由Ru2对氮起反馈作用的轨道数目决定.一般来说，氮氮键活化越强，体系能量越高，在相同的活化程度下，自旋多重度高的体系较稳定.     

HNNH3的从头计算研究

Ab-Initio studies applying the 3-21G, 6-31G and 6-31G** basis sets and also including the MP2 correction were carried out on H2NNH2, HNNH3 and the transition state molecule of the reaction H2NNH2=HNNH3. First, the geometry of the three molecules was optimized using the theoretical methods mentioned in the Hartree-Fock(HF) scheme. The energies of the molecules corresponding to RHF/6-31 G** geometries were subsequently calculated including electron correlation effects at the level of the second-order Moller-Plesset(MP2) perturbation theory. The vibrational frequencies, net charges and dipole moments were obtained from the theoretical calculations. The results of our ab-initio calculations indicate unambiguously that H2NNH2 is thermodynamically more stable than HNNH3. On the other hand, an isolated HNNH3 molecule once created would be rather stable since barriers for its unimolecular isomerization and decomposition are relatively high. Nevertheless, HNNH3 can be considered as an intermediate in chemical processes involving N2H4. This assumption has been supported by further calculation at higher level of theory.     

聚丁二炴的能量和能带结构计算

本文采用LCAO_SCF ab initio晶体轨道方法计算了聚丁二炔的两种可能结构: 乙炔型结构C(R—C≡C—CR′)和丁三烯型结构(_nCR=C=CR′)_n的能量和能带结构; 讨论了不同侧链基团聚丁二炔的两种结构的能量稳定性及其能带结构的变化; 并从侧链基团的性质及这两种结构的差别进行了分析, 较好地解释了计算结果。     

RuN2分子结构和振动光谱的理论研究

使用钌原子相对论有效原子实势LanL2dz和密度泛函理论B3LYP方法对RuN2分子结构与分子光谱进行理论研究。结果表明RuN2分子基态为线性C∞v端配结构,基态电子态为3△,平衡几何为RRu-N=0.1910 nm,RN-1=0.1120 nm。同时首次计算给出各种稳定结构的振动频率,红外强度,拉曼活性与退极化率和偶极矩。     

理论研究BrCl~ 低激发电子态势能曲线和光谱性质

应用量子化学中高等级的多参考组态相互作用方法计算了环境科学中重要的分子离子BrCl 的基态和低激发态的势能曲线与光谱常数,详细分析了旋轨耦合作用对电子结构和光谱性质的影响,确认了基态X2Π和低激发电子态的多组态特征,得到了基态X2Π的旋轨耦合分裂能1814cm-1,与实验值2070cm-1接近.预测了2Π(Ⅱ)态的旋轨耦合分裂能为766cm-1.估算了3/2(Ⅲ)-X3/2和1/2(Ⅲ)-1/2(Ⅰ)跃迁的偶极跃迁矩和Frank-Condon因子,讨论了它们的跃迁辐射寿命.     

碱基与氮甲基乙酰胺相互作用的从头算和ABEEMσπ研究

选取氮甲基乙酰胺(N-Methylacetamide,NMA)和DNA碱基为研究对象,应用ABEEMσπ/MM方法研究了NMA与碱基之间形成的二聚体的几何构型、电荷分布及结合能等性质,并进行了相应的从头算(abinitio)MP2水平研究,在B3LYP/6-311 ++G(d,p)水平下对结构进行了优化.将2种方法的研究结果进行比较发现,所获得的构型、电荷及结合能之间具有很好的一致性,NMA与DNA碱基相互作用的强度大小依次为:鸟嘌呤＞胸腺嘧啶＞胞嘧啶＞腺嘌呤,且证明了ABEEMσπ/MM模型的参数具有很好的可转移性.     

碱基与氮甲基乙酰胺相互作用的从头算和ABEEMσπ研究

选取氮甲基乙酰胺(N-Methylacetamide,NMA)和DNA碱基为研究对象,应用ABEEMσπ/MM方法研究了NMA与碱基之间形成的二聚体的几何构型、电荷分布及结合能等性质,并进行了相应的从头算(abinitio)MP2水平研究,在B3LYP/6-311 ++G(d,p)水平下对结构进行了优化.将2种方法的研...     

单重态H_2N=B:→HNBH重排反应的理论研究

用量子化学中的从头算方法, 在MP2/6-311++G(d,p)水平上研究了单重态H_2N=B→HNBH重排反应的机理。结果表明, 该重排反应经过一个三元环过渡态。根据计算结果，初步讨论了该反应的热力学及动力学函数。     

2-甲基-6-二乙胺基乙氧基-3(2H)-哒嗪酮的合成及其电子性质

分别利用两种方法合成2－甲基－6－二乙胺基乙氧基－3（2H）－哒嗪酮，用^1H NMR,IR,UV和MS进行结构表征，利用ab initio HF和密度泛函理论（DFT）B3LYP方法，对反应物、中间物、产物及其同分异构体进行几何结构的优化和总能量计算，系统分析前线分子轨道特征和能级分布规律，结果表明，2－甲基－6－二乙胺基乙氧基－3（2H）－哒嗪酮比其同分异构体哒嗪氮烷基化合物的能量低，前比后稳定，与实验事实相符合。     

N2+分子离子的B2Σu+、A2Πu和X2Σg+电子态光谱研究

采用光外差-磁旋转-速度调制吸收光谱技术, 在可见光波段范围16800～17573 cm-1, 对N2+的A 2Πu-X 2Σ+g(12,6)、(11,5)、(7,2)带和B 2Σ+u-X 2Σ+g (1,5)带进行了测量和分析,推导了双原子分子振转能级在受到微扰作用时的有效哈密顿量形式,并分析了N2+的A 2Πu-B 2Σ+u之间存在的微扰相互作用,通过与实验数据的拟合得到了精确的电子态微扰常数ξe、ηe .     

Electronic Structure of the Low-Lying States of the Triatomic MoS2 Molecule: The Building Block of 2D MoS2

Molybdenum disulfide (MoS₂) is the building component of 1D-monolayer, 2D-layered nanosheets and nanotubes having many applications in industry, and it is detected in various molecular systems observed in nature. Here, the electronic structure and the chemical bonding of sixteen low-lying states of the triatomic MoS₂ molecule are investigated, while the connection of the chemical bonding of the isolated MoS₂ molecule to the relevant 2D-MoS₂, is emphasized. The MoS₂ molecule is studied via DFT and multireference methodologies, i. e., MRCISD(+Q)/aug-cc-pVQZ(−PP)_Mo. The ground state, ³B₁, is bent (Mo−S=2.133 Å and ϕ(SMoS)=115.9°) with a dissociation energy to atomic products of 194.7 kcal/mol at MRCISD+Q. In the ground and in the first excited state a double bond is formed between Mo and each S atom, i. e., . These two states differ in which d electrons of Mo are unpaired. The Mo−S bond distances of the calculated states range from 2.108 to 2.505 Å, the SMoS angles range from 104.1 to 180.0°, and the Mo−S bonds are single or double. Potential energy curves and surfaces have been plotted for the ³B₁, ⁵A₁ and ⁵B₁ states. Finally, the low-lying septet states of the triatomic molecule are involved in the material as a building block, explaining the variety of its morphologies.     

Synthesis and Electronic Properties of 6-Chloro-2-diethylaminoethyl-3(2H)-pyridazinone

6-Chloro-2-diethylaminoethyl-3(2H)-pyridazinone was synthesized by the reaction of 6-chloro-3(2H)-pyridazinone and 2-diethylamionethyl chloride reaction in methylbenzene.Then the structure was characterized by means of ^1H NMR,IR,UV.By the method of ab initio HF and density functional theory(DFT) BeLYP,the geometric structures of the reagent intermediate,the product and its isomer were optimized and their total energies were calculated,The properties for the frontier molecular orbitals and the rules for energy distribution were analyzed systematically.It was shown that the energy of the nitrogen alkyl compound is lower than that of the oxy alkyl compound and the former is stable than the latter.This result is in accordance with the fact that 6-chloro-2-diethylaminoethyl-3(2H)-pyridazinone is synthesized by the reaction of 6-chloride-2-diethylaminoethyl-3(2H)-pyridazinone and 2-diethylaminoethyl chloride.     

Electronic Structure of the Ground and Excited States of β‐Carboline

Coupled‐cluster calculations are used to compute the energy of conversion between the neutral and the zwitterionic forms of β‐carboline. The stability of the different species is discussed in terms of charge separation and aromatic character, which is related to magnetic criteria. By means of a linear response formalism the vertical excitation energies and oscillator strengths of the lowest singlet states of both structures as well as of the cationic species are determined. General agreement of the relative position and intensity of the different peaks with experimental data is achieved, but the overall spectra are slightly displaced because of solvent effects.     

Theoretical investigation on regioselectivity of aromatic ketones in the addition with olefin catalyzed by RuH2(CO)(PPh3)3

Ab initio method is employed to study the structures of twelve aromatic ketones at HF/3-21G, HF/6-31G and HF/6-31G levels, respectively. A theoretical analysis is also carried out to study the regioselectivity and reactivity of aromatic ketones in the addition with olefin catalyzed by RuH2(CO)(PPh3)3. The results indicate that a U shape LUMO conjugation of aromatic ketones in a plane plays an important role in regioselectivity on the cleavage of p C-H bond and is a nec-essary factor to success of addition with olefin, and that sterle effect is an indispensable factor in forming additional ortho-product. Meanwhile, electronic effect may influence the rate of addition for the structures alike which only have different replacements in the same site of aromatic ring, such as furan, thiophene and pyrole. A possible catalytic reaction mechanism is proposed that the addition of C-H bond may be carried out by a coordination of aromatic ketones with Ru complex.     

HNNH3, a new possible isomer of N2H4: An ab initio study

Ab initio studies applying the 3-21G, 6-31G, and 6-31G** basis sets and also including the MP2 correction were carried out on H₂NNH₂, HNNH₃, and the transition state of the reaction H₂NNH₂(DOUBLE BOND)HNNH₃. First, the geometries of molecules were optimized using the theoretical methods mentioned in the restricted Hartree–Fock (RHF) scheme. The energies of the molecules corresponding to RHF/6-31G** geometries were subsequently calculated including electron-correlation effects at the level of the second-order Møller–Plesset (MP2) perturbation theory. The vibrational frequencies, net charges, and dipole moments were obtained from the theoretical calculations. The results of our calculations indicate unambiguously that H₂NNH₂ is thermodynamically more stable than is HNNH₃. On the other hand, an isolated HNNH₃ molecule once created would be stable since barriers for its unimolecular isomerization and decomposition are relatively high. But HNNH₃ is unlikely to be isolated in measurable amounts because of bimolecular tautomerization. Nevertheless, HNNH₃ can be considered as an intermediate in chemical processes involving N₂H₄. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 64 : 447–452, 1997     

H8Si8O12和H8Si7TiO12 团簇的几何构型和电子结构的从头算研究

应用HF、 MP2和杂化的B3LYP方法,使用3-21G基组,对H8Si8O12 和H8Si7TiO12团簇的几何构型、总能进行了计算,并在B3LYP/3-21G的水平上对硅原子的核磁共振化学位移进行了研究,得到的几何构型,以及核磁共振化学位移与实验结果进行了比较,发现吻合得很好。计算了H8Si8O12和H8Si7TiO12团簇的Mulliken布居数的大小。并对Si原子被Ti原子取代前后的H8Si8O12体系的几何构型、 Mulliken布居数的变化进行了比较和研究。     

8-羟基喹啉铝光电性质的Ab initio和DFT研究

利用abinitioHF和密度泛函理论B3LYP等方法,对金属有机配合物8-羟基喹啉铝(AlQ₃)进行几何结构优化,探索分子内部电子跃迁的机理.结果表明,电子从基态跃迁到低激发态时主要为π-π^*跃迁;电荷从含氧的苯酚环转移至含氮的吡啶环上,包括两环之间C→C转移和O→N转移,与金属离子关系不大.考虑到配体对发光性质的贡献,进一步设计了3种AlQ₃的衍生物.     

五氧化二氮和水反应的从头算研究

在臭氧空洞形成过程中,极地云是一个重要的条件。为了理解极地云的形成和性质,采用不同水平的从头计算方法对N~2O~5+H~2O→2HNO~3反应进行了理论研究。在QCISD(T)//MP2/6-311G(d,p)理论水平上,该气相反应的焓变△H^0=-39.5kJ·mol^-^1,自由能变化△G^0=-36.1kJ/mol,活化能E~a=88.2kJ·mol^-^1(298K)。计算的结果与五氧化二氮易潮解的性质相符。     

卤素氮氧化物的结构和光谱性质的理论研究

通过DFT/B3LYP计算,优化了卤素氮氧化物XNO_2及其异构体XONO（X = F,Cl ,Br,I）的平衡几何构型,预测了异构体的相对稳定性及其相互转化的活化能垒 。在B3LYP和QCISD（T）计算水平上,确定了X-NO_2键的解离能。应用与时间有关 的密度泛函理论（TD-B3LYP）计算了XNO_2低激发态的跃迁能,并讨论了这些激发 态与卤素氮氧化物光诱导解离过程的关联。