取代硅烷系列分子二阶非线性光学性质的ZINDO-SOS研究

在ZINDO方法基础上, 按完全态求和(SOS)公式, 自编了计算分子二阶非线性光学系数βijk的程序, 考察了取代硅烷分子中与硅原子相连的苯环上取代基的变化及链长变化对分子二阶非线性光学的影响, 重点研究了(CH3)3Si基团的性质, 对计算结果所反映的规律性在微观上给予了解释。     

ELECTRONIC STRUCTURE AND CRYSTALLINE ELECTRIC FIELD IN Rco5(R= Y,La, Ce,Pr, Nd,Sm, Gd,and Tb)

Self consistent charge and spin polarized local spin-density approximation functional theory calculations based on the discrete variational method have been performed for RCo₅(R=Y, La, Ce, Pr, Nd, Sm, Gd, and Tb) compounds. The partial density of states of the Pr atom in the PrCo₆Co₁₂ cluster is established to be strikingly similar to that of the Ce atom in the CeCo₆Co₁₂ cluster, supporting the suggestion that the Pr atom is valence fluctuating. The radii ＜r_4f＞ and ＜r₄f²＞ of the 4f electrons of the R atom from La to Tb, except Ce, show the lanthanide contraction. The crystalline electric field (CEF) parameter A⁰₂ at the R site is calculated using a real charge distribution ρ(R) in the cluster, except for Pr and Nd, and is in agreement with that evalu ated based on the single-ion model. This result shows that the CEF parameter A⁰₂ is mainly determined by the near electronic structure. There exists a hybridization in a certain degree between the light rare-earth R-4f and Co-3d orbitals in some single-electron-molecular-orbitals, which are n ear the Fermi energy level and occupied by electrons. For light rare-earths the R-4f electrons in R Co₆Co₁₂(R=Y, La, Ce, Pr, Nd, and Sm) clu sters are not localized entirely and a small amount of the R-4f electrons have itinerant properties.     

C59O的结构、电子光谱及NMR谱的理论预测

用INDO系列方法对C₆₀的取代产物C₅₉O进行几何构型优化,得到Cs对称性的稳定构型,以此构型为基础,计算并预测了C₅₉O的电子光谱和NMR谱.最后与C₅₉O的等电子分子体C₆₀^2-及C₆₀O进行了比较.     

硅硫团簇[(SiS2)nS]+(n=1～4)的结构及振动光谱的量子化学研究

用密度泛函(DFT)方法(B3LYP/6-31G*)研究了硅硫团簇[(SiS~2)~nS]^+(n=1～4)的可能几何构型,得到各稳定构型的电子结构,并计算了相应的振动频率,预测了稳定构型的振动光谱。由其稳定构型的比较可在理论上预测团簇的生长规律,并可初步预测团簇的形成机理。     

HPO_2异构体结构和相对稳定性

在MP2/6-311++G（d,p）和QCISD（t）/6-311++G（3df,2p）（单点）水平下计算得到了包括8个异构体和12个过渡态的HPO2体系势能面.在势能面上,异构体cis-HOPO（EI）的能量是最低的,其次是trans-HOPO（E2）和HPO（O）（C2v,E3）,能量分别比cis-HOPO高10.99和48.36 kJ/mol.根据体系的势能面,只有异构体E1和E3具有较高的动力学稳定性,在实验中应该可以观测到.PH和O2直接反应生成的cis-HPOO（E5）和trans-HPOO（E6）经过几步势垒较低的异构化过程就可以异构化为具有较高动力学稳定性的产物E1;而OH和PO反应可直接生成E1.计算结果较好地解释了相关实验.     

CH3O2·+ClO气相反应的密度泛函理论研究

用密度泛函方法在CCSD(T)/ 6-311++G// B3LYP/ 6-311G**水平上研究了气相反应CH3O2*+ClO的反应机理.得到了不同能量产物的可能的反应通道,获得反应势能面.整个反应过程为多通道反应,经过多个步骤完成,共找到7个中间体和10个过渡态,产物1CH3OCl+3O2(P1)和1 CH2O+1HOOCl(P4)为能量较低产物,通道1a:R→IM1→TS1/ 3→IM3→P1,4a:R→IM1→TS1/ P4→P4和4b:R→IM2→TS2/ P4→P4为较为可行的反应通道.     

Ultrahigh Harmonic Generation from an Atom with Superposition of Ground State and Highly Excited States

We investigate the high-order harmonic generation from an atom prepared in a superposition of ground state and highly excited state. When the atom is irradiated by an ultrashort pulse, the cutoff position of the plateau in the harmonic spectrum is largely extended compared with the case that the atom is initially in the ground state. The physics of the extension of the high-order harmonic plateau can be interpreted by the spatial structure of the atomic initial wave packet. We can optimize the generation of high-order harmonics by substituting the excited state for a particular coherent superposition of some highly excited states to form a spatially localized excited wave packet.     

Theoretical study on second-order nonlinear optical properties of unsymmetric bis (phenylethynyl) benzene series derivatives

On the basis of ZINDO methods, according to the sum-overstates (SOS) expression, the program for the calculation of the second-order nonlinear optical susceptibilities βijk and βμ of molecules was devised, and the structures and nonlinear optical properties of unsymmetric bis (phenylethynyl) benzene series derivatives were studied. The influence of the molecular conjugated chain lengths, the donor and the acceptor on βμ was examined.     

碱金属化物M+aza222M′- (M,M′=Li,Na, K)的结构及非线性光学性质

采用密度泛函理论(DFT)B3LYP方法得到具有有机穴状配体的碱金属化物M+aza222M′-(M,M′=Li,Na,K)的几何结构.并使用了BHandHLYP方法计算了此体系的非线性光学(NLO)性质.结果表明:该体系具有很大的一阶超极化率(β0),对于Li+aza222K-体系,β0值达到1.0×106a.u.;体系的β0值及配体aza222内外的碱金属之间距离与碱金属的原子序数均存在着依赖关系.通过与其它碱金属化物的β0值对比发现,aza222配体能够显著增大碱金属化物的一阶超极化率.     

溶液中类锗烯H2GeClMgCl的结构与异构化反应

用密度泛函理论(DFT)和QCISD(quadratic configuration interaction with single and double excitations)方法研究了类锗烯H2GeClMgCl在气相和五种溶剂中的构型与异构化反应. 结果表明, 类锗烯H2GeClMgCl有三种平衡构型. 其中p-配合物型构型能量最低, 是其存在的主要构型. 讨论了溶剂效应对结构、能量与异构化反应的影响. 计算模拟了最稳定构型的红外光谱.