孪函数N电子基组的组态

分析了各类孪函数Ｎ电子基组态展开式的特点以及它们对体系相关能的贡献，提出了一种在享函数Ｎ电子基矢下进行多组态自洽场计算时的组态选取方法，并依此方法在ＳＴＯ－６－３１Ｇ基组下对ＬｉＨ分子的基态能量做了计算，结果表明，用该组态选取方法只需选取少量的组态波函数便可得到相当精确的计算结果。     

Ne原子的精确二阶超极化率

为了获得精确的Ne原子的二阶超极化率,基组必须包括三部分φ=φ^(0) φ^(1) φ^(2)。其中φ^(0)由s,p函数组成,必须能较完备地描述无外电场时原子的波函数,使无微扰能量E0接近Hartree-Fock极限值,同时对远离核的区域的电子云有较好的描述。Φ^(1)由d函数组成,必须能较完备地描述外场引起的一阶微扰,使极化率α接近Hartree-Fock极限值。Φ^(2)由f函数组成,必须能较完备地描述外场引起的二阶微扰,使超极化率γ接近Hartree-Fock极限值。基组的三部分依次分别对E0,α和γ进行优化,从而排除了基组选择过程中的任意性,使计算结果随着基组的扩大而无限趋近Hartree-Fock极限值。用35s20p10d7f基组的计算结果是γ(SCF)=68．83,可用来纠正数字轨道的结果。用其收缩后的基组17s11p10d7f计算的相关水平的结果与实验值符合。     

基态XO~（n＋）（X=Ru,Rh,Pd;n=0,1）的势能函数和第一垂直电离势

运用原子分子反应静力学原理推导出XOn+(X=Ru,Rh,Pd;n=0,1)的基态电子状态及离解极限.运用密度泛函的B3P86方法和LANL2DZ赝势基组及aug-cc-pVTZ全电子基组,对XOn+X=Ru,Rh,Pd;n=0,1)体系进行计算,获得了这些分子及其离子基态的Murrell-Sorbie解析势能函数.同时计算了XOn+(X=Ru,Rh,Pd;n=0,1)的光谱数据,计算了XO(X=Ru,Rh,Pd)中性分子的第一垂直电离势.     

孪函数N电子基向Slater多电子反对称基的展开

发展了一套孪函数多电子基向Slater行列式的展开方法,并得到展开系数的解析表达式,使得孪函数多电子基直接与Hartree-Fock从头计算相关联.     

基态XOn+(X=Ru,Rh, Pd|n=0, 1)的势能函数和第一垂直电离势

运用原子分子反应静力学原理推导出XOn+(X=Ru, Rh, Pd; n=0, 1)的基态电子状态及离解极限. 运用密度泛函的B3P86方法和LANL2DZ 赝势基组及aug-cc-pVTZ全电子基组, 对XOn+(X=Ru, Rh, Pd; n=0, 1)体系进行计算, 获得了这些分子及其离子基态的Murrell-Sorbie解析势能函数. 同时计算了XOn+(X=Ru, Rh, Pd; n=0, 1)的光谱数据, 计算了XO(X=Ru, Rh, Pd)中性分子的第一垂直电离势.     

系列杂氮钛三环中的分子内弱相互作用的紫外光电子能谱和理论研究

首次报道了四种杂氮钛三环的紫外光电子能谱,结合量子化学从头算和和电子密度拓扑分析方法对这些化合物的电子结构和分子内存在的弱相互作用进行了分析研究。通过优化STO-6G(d)基组(C:1s=5.66,ζ2s=1.675,ζ2p=1.66;O:ζ1s=7.67,ζ2s=2.25,ζ2p=2.20;N:ζ1s=6.66,ζ2s=1.91,ζ2p=1.89;H:ζ1s=1.24)对所研究的化合物进行了分子轨道计算,结合计算结果对化合物的紫外光电子能谱进行了解析和指认。实验得到的体现分子内弱相互作用σN-Ti的轨道电子的电离能表明了N,Ti间相互作用的弱成键特性,电子密度拓扑分析显示N,Ti原子间存在体现成键作用的键鞍点,键鞍点处电子密度的拓扑性质也进一步支持了N,Ti间弱成键作用的特性。     

从头计算法分子轨道绘图程序

在前文中,我们报道了以Slater函数(STO)和类氢函数为原子轨道基组的分子轨道绘图程序,文介绍以Gauss函数(GTO)为基组的从头计算分子轨道绘图程序,该程序可绘制各类型(s,p,d等)GTO表示的原子轨道和以STO-GTO系基组构成的各种分子轨道ψ或|ψ|²的截面立体图及等值图,利用从头计算的结果,所绘制的图形能很好的反映从头计算法本身的特点。     

非线性光学极化率密度泛函理论计算的基组效应

由于分子的非线性光学性质与分子外层电子行为及激发性质密切相关,扩散函数对分子的非线性光学极化率计算非常重要.在ADF程序中的DZP基组基础上缀加扩散函数,构造出我们称之为DZP+df的新基组.通过对5个模型分子的含频二阶非线性光学极化率的密度泛函理论计算,表明新基组可以得出较DZP基组更为准确可靠的结果,同时比较ADF程序内置带有扩散函数的大基组,计算量大为减少.     

PF(X~3∑~-)的结构、势能函数与光谱常数

运用多种方法、多种基组对PF(X3∑-)的平衡结构进行优化计算.用QCISD/6-311G(df)方法得到的平衡结构为RPF=0.158 9 nm,与实验值RPF=0.158 97 nm进行比较,最为接近,得出QCISD/6-311G(df)基组为最优基组;然后对PF(X3∑-)进行单点能扫描计算,用正规方程组拟合Murrell-Sorbie函数,得到相应电子态的势能函数解析式,由势能函数计算了与PF(X3∑-)态相对应的光谱常数,结果与实验数据较为一致.这些数据为反应动力学提供了理论依据.     

全氟代金刚烷及其自由基的理论研究

采用密度泛函理论(DFT)方法:BHLYP、B3LYP、BP86、BLYP,在全电子的双ζ基组加极化函数和弥散函数(DZP＋)基组下,计算了全氟代金刚烷(C10F16)及其自由基(C10F15)的总能量、优化几何构型、电子亲和势和谐振频率.在B3LYP水平上所得到的可靠绝热电子亲和势(EAad)分别为: C10F16, 1.06 eV; C10F15, 4.11和 3.03 eV.     

On geminals and symplectic bases in quantum chemistry

The construction of a symplectic basis set with >N electrons is exhibited by means of three kinds of units, the first kind geminal, the second kind geminal and the one‐particle operators. The optimization procedure of the variation method is extended to the coefficients in the linear sum of the symplectic bases, the parameters in the geminals, and the orbitals. For practical use, these bases are expanded explicitly as a linear sum of the Slater determinants. For illustration, the LiH molecule, which is taken as an example, is calculated by using some symplectic bases. This revised version was published online in July 2006 with corrections to the Cover Date.     

The Wave Function with Symplectic Symmetry and Its Application

The antisymmetrized geminal power (AGP) and sequential product of geminals(SPG) functions, the basis functions with symplectic symmetry, are linearly combined to calculate the ground state of the LiH molecule. The calculation results show that the AGP or SPG function gives the same ground state results as the linear combination.     

A new functional for variational calculation of atomic and molecular second-order correlation energies

Second-order correlation energies for atoms and molecules are calculated with a novel variational functional that is closely related to the one used before but neglects the most time-consuming terms. Consequently much larger basis sets could be used. Results for He, Be, H₂ and LiH obtained with an explicitly correlated gaussian geminal basis are better than the best published results by 0.32, 0.06, 3.3, and 6.2% and are estimated to be accurate to within a fraction of 1%.     

Electron correlation described by extended geminal models: The EXGEM4 and EXGEM5 models

Within the framework of the general extended geminal model, two new approximate models EXGEM 4 and EXGEM 5 are introduced. The models are tested against full CI calculations on the water molecule for three different nuclear configurations and a full CI potential energy curve for the LiH molecule in the ground state. On the basis of these calculations, it is suggested that the models will yield electronic correlation energies with an accuracy of 1–2% of the corresponding full CI result.     

An extended geminal model calculation of the dissociation energy of the ground state of Li2

The dissociation energy of the ground state of the Li₂ molecule has been calculated by using an extended geminal model. The calculated result is 1.024 eV and the experimental value is 1.048 ± 0.012 eV. the discrepancy can at least partly be attributed to a deficiency in the orbital basis set.     

LiH分子X 1Σ+ 、A 1Σ+和B 1Π态的势能函数

The energies, equilibrium geometries and harmonic frequencies of the three electronic states (the ground state X 1Σ+, the first excitation state A 1Σ+ and the second excitation degenerate state B 1Π) of LiH molecule have been calculated by using the GSUM (Group Sum of Operators) method of SAC/ SAC-CI with the basis sets D95(d), 6-311G**, and cc-PVTZ. Comparing with the above-mentioned three basis sets, the conclusion is gained that the basis set D95(d) is the most suitable for the energy calculation of LiH molecule. The whole potential curves for these three electronic states are further scanned, using SAC/D95(d) method for the ground state and SAC-CI/D95(d) methods for the excited states. Murrell-Sorbie function were fitted using a least square and then the spectroscopy constants are calculated, which are in good agreement with the experimental data.     

Direct energy minimization of self-consistent electron pair by an orthogonal transformation of the basis

In the frame of direct minimization of MC–SCF energy by an orthogonal transformation of the basis, a new procedure for iteratively solving the orbital equations is presented, in which the orthogonal matrix is calculated by the singular value and vector decomposition of a nonsymmetric matrix. The procedure is applied to the self-consistent electron pair theory and tested on LiH molecule. Convergence rate and numerical stability are found to be satisfactory.     

A computational study of the LiH dimer

A theoretical study of the properties of the linear LiH dimer was undertaken. In this dimer, an unusual type of hydrogen bonding (termed "inverse" hydrogen bonding by some authors), which involves the hydrogen bonded molecule acting as an electron donor (rather than as a proton donor), is exhibited. The optimized geometry, dipole moment, interaction energy, atomic charges, harmonic vibrational frequencies, and frequency shifts for the dimer are computed at the SCF, MP2, and QCISD levels of theory using mainly a 6-31++G(d,p) basis set. We also examined the relative stability of the mono-deuterated isotopomers of linear (LiH)(2), i.e., Li-H...Li-D and Li-D...Li-H. Analysis of the normal vibrational modes, changes in the partial atomic charges, and changes in the vibrational frequencies of LiH on complexation were used to gain insight into the bonding and properties of the linear LiH dimer and its isotopomers.