Wick定理及约化密度矩阵的重构方案

利用外积获得了Wick定理的封闭表达式, 并给予了严格的证明. 新的表示式类似于二项式展开. 利用这一新形式, 推导出了约化密度矩阵的重构方程. 高级约化密度矩阵系统地分解为低级约化密度矩阵的和. 有了这些重构方程便可以求解简宿Schrödinger方程(contracted Schrödinger equation).     

稀土离子Pr3+和Tm3+多重态间电偶极跃迁约化矩阵元的计算

利用M.F.Reid的f壳层经验程序和P.A.Tanner发表的氯冰晶石Ca2NaLnCl6体系中Pr3+和Tm3+离子的能级参数计算出它们的基组态的中间态波函数14fN?SLJ(共13个),然后将其代入单位张量算符U(?)(?=2,4,6)的约化矩阵元公式中,分别计算出Pr3+和Tm3+离子的各个多重态之间电偶极跃迁的约化矩阵元的值.对该约化矩阵元在分析激发态吸收几率或能量传递几率的应用做了讨论.     

密度矩阵重正化群计算电子激发态的算法比较研究

激发态电子结构计算是理论与计算化学领域中的重要问题.本文测试了密度矩阵重正化群理论的state specific激发态算法,并在Pariser-Parr-Pople(PPP)模型下以并苯体系和聚乙炔体系为例对state specific算法和传统的态平均激发态算法进行了比较.计算结果表明,state specific算法可以正确地跟踪较低的激发态,并能得到比态平均算法更精确的能量本征值;在高激发态的计算过程中,state specific算法可能出现收敛于错误本征态的问题.     

SmP_5O_(14)晶体中的辐射跃迁

本文根据Judd-0felt理论,计算了SmP_5O_(14)晶体中Sm~(3 )离子的振子强度和参数Ω_λ实验值和计算值符合较好。同时计算了~4G_5/2→~6H_J跃迁的约化矩阵元和辐射跃迁几率。     

过渡金属络合物荷移光谱的研究

在配位场近似下,用不可约张量方法对具有O_4对称性的FeCl_6~(3-)及与其结构相似的过渡金属络合物的Hamilton矩阵进行了矩阵分割,得到了一种计算荷移光谱的简单方法.在计算中采用方案,考虑了纯组态内部的Coulomb作用和旋轨作用,忽略了不同组态间的Coulomb作用.并采取冻结轨道近似.计算结果与实验光谱数据符合较好.     

势阱中粒子能级与波函数微扰计算的代数递推公式

利用超位力定理(HVT)和Hellmann-Feynman 定理(HFT),导出了由有精确解的势阱的能级值用微扰法直接计算一维势阱的各级近似能级的普遍代数公式,并导出了由能级近似值计算定态波函数近似表达式的代数公式.给出了代数公式具体应用的几个典型一维势阱实例.此法可推广到二维势阱与三维势阱的情形.     

生物体系中电子转移机理的理论研究 I.一种计算电子转移的方法及在螺环化合物中的应用

应用"相应轨道变换"和"广义"密度矩阵的方法,向MOPAC程序包中加入了新的功能,使其能处理电子转移反应中的部分参数.然后用此程序包中AM1方法对具有螺环结构的分子进行处理,计算了化合物在不同外加电场强度下的势能面、反应热△E,重组能λ及电子转移矩阵元VAB,结果表明,λ,VAB受外加电场的影响较小,而△E则与之成正比.对标题化合物1的计算结果也同ab initio法的结果进行了比较,发现其变化趋势完全一致,这说明本方法在计算电子转移方面是可靠的.与ab initio方法相比,本程序不仅适用于计算较大体系(如生物大分子),而且还具有速度快,耗时少的优点.     

SmP5O14晶体中的辐射跃迁

本文根据Judd-0felt理论,计算了SmP₅O₁₄晶体中Sm³⁺离子的振子强度和参数Ω_λ实验值和计算值符合较好。同时计算了⁴G₅/2→⁶H_J跃迁的约化矩阵元和辐射跃迁几率。     

按非刚性转子模型计算NF3和环氧乙烷的光谱熵

NF_3和环氧乙烷(C_2H_4O)作为推进剂,曾由Sundaram按刚性转子-谐振子模型计算了其光谱熵.但由于忽略了离心力的影响,必然致使计算结果偏低(尤其在高温下).本文按Kivelson等给出的离心力校正参数τ值与离心力伸长常数D_J、D_(JK)和D_K间的关系式,由微波谱给出的数据计算了C_2H_4O的离心伸长常数(表1).改按非刚性转子—谐振子模型,采用直接加和法重新精确计算转动、振动配分函数,进而在100～2000K范围内计算了NF_3和C_2H_4O的光谱熵(表2).比较了所得结果与Sundaram的计算值     

CoH生成热力学函数的量子力学计算

用B3LYP/SDD密度泛函方法计算了CoH的微观性质、CoH(g)、CoD(g)和CoT(g)的能量(E)和熵(S),进而计算Co与H2、D2、T2反应的△H(-)、△G(-)、△S(-).CoH分子的基电子状态为三重态,Re、D(-)0、ωe分别为1.52nm、277.84 kJ/mol和1321 cm-1,与实验值基本一致.在固态分子的E和S的计算中,以气态分子计算得到的总能量中的振动能Ev代替固态能量,以总熵中的电子振动熵SEv代替固态熵.导出了Co与氢同位素气体反应的△H(-)、△G(-)、△S(-)及平衡氢压力与温度的关系.CoH的室温下平衡离解压力很低,表明CoH是一种稳定的氢化物,这与CoH分子的D(-)0很大的实验事实一致.     

卟啉酞菁模型化合物光致电子转移研究

本文采用时间相关单光子计数对卟啉酞菁ＴＴＰ－（ＣＨ２）ｎ－Ｐｃ模型化合物的光致电子转移进行了研究，发现激发Ｐｃ时，呈现单指数衰减，ｎ＝４时电子转移速率减小，活化能，重排能增加，电子转移效率下降，电子转移反应△ＧＣＳ与电荷分离活化络合物衰变速率ＫＣＴ，按以下规律：△Ｇ＾（５）ＣＳ〉△＾（３）ＣＳ〉△＾（４）ＣＳ〉△＾（２）ＣＳ，ｋ＾（２）ＣＳ〉ｋ＾（３）ＣＳ〉ｋ＾（４）ＣＳ〉ｋ＾（５）ｃｓ。其△Ｇ＾     

On the contribution of higher-order excitations to correlation energies: The ground state of the water molecule

Using the results of a configuration interaction calculation reported by Rosenberg and Shavitt, we derive an approximation to the correlation energy which may be associated with the sum to infinite order of all linked diagrams involving singly- and doubly-excited states. This result is compared with that obtained by calculation of the energy through third-order. The fourth-order linked diagrams involving quadruply-excited states are computed. It is shown that there is a considerable degree of cancellation between the fourth-order linked diagram energy terms involving doubly-excited intermediate states only and those which contain quadruply-excited states.     

Conformation-specific Raman bands and electronic conjugation in substituted thioanisoles

Nonresonant Raman spectra and conformational stability are studied for thioanisole (TA) and substituted analogues [4-XTA, X = NO(2) (1), CN (2), H (3), CH(3) (4), and NH(2) (5)] at the 4-position. The ring-substituent (SCH(3)) vibrational modes of out-of-plane bending and torsional types are calculated to have strong Raman scattering activities only for the vertical conformers. Agreement between observed and calculated Raman spectra is analyzed numerically. The conformational stability of the SCH(3) rotation changes systematically to the electron-withdrawing character of the substituents. The rotational barrier is calculated satisfactorily by B3LYP/6-31++G(d,p) calculations, whereas the second- to fourth-order M?ller-Presset perturbation theory and coupled-cluster with single- and double-excitation calculations tend to overestimate conformational energy barriers with respect to coplanar forms. The coplanar form is obtained for 1 and 2, whereas the vertical conformer is favorable for 4 and 5. The origin of the conformational energy difference, DeltaE, is demonstrated on the basis of canonical molecular orbitals and natural bond orbitals (NBOs) of the ground state. The natural bond orbital interaction between a nonbonding n(S) orbital of the S atom and a pi orbital of the benzene ring is shown to stabilize the coplanar form predominantly. A linear relationship is obtained between the energy of the highest occupied molecular orbitals and DeltaE. The n(S)-pi interaction energy, E(2), based on the NBO representation and the Hammet constants also change linearly with respect to DeltaE.     

Ab initio vibrational state calculations with a quartic force field: applications to H2CO, C2H4, CH3OH, CH3CCH, and C6H6

For polyatomic molecules, n-mode coupling representations of the quartic force field (nMR-QFF) are presented, which include terms up to n normal coordinate couplings in a fourth-order polynomial potential energy function. The computational scheme to evaluate third-and fourth-order derivatives by finite differentiations of the energy is fully described. The code to generate the nMR-QFF has been implemented into GAMESS program package and interfaced with the vibrational self-consistent field (VSCF) and correlation corrected VSCF (cc-VSCF) methods. As a demonstration, fundamental frequencies have been calculated by the cc-VSCF method based on 2MR-QFF for formaldehyde, ethylene, methanol, propyne, and benzene. The applications show that 2MR-QFF is a highly accurate potential energy function, with errors of 1.0-1.9% relative to the experimental value in fundamental frequencies. This approach will help quantitative evaluations of vibrational energies of a general molecule with a reasonable computational cost.     

Near-degeneracy effects and efficiency of MBPT calculations of molecular properties. Polarizability curve of H2

The polarizability curve of H₂ is calculated by using the finite-field perturbation method. All self-consistency effects are accounted for at the HF level and many-body perturbation theory (MBPT) is used to evaluate the correlation contributions. Using a single HF determinant as a reference in MBPT calculations makes the near-degeneracy effects of essential importance on increasing the interatomic distance. Nevertheless, applying the MBPT scheme with appropriate fourth-order terms gives nearly exact values of both components of the polarizability tensor for interatomic distances up to ≈3.6 au.     

8-（3-或4-氟苯甲酰基）-7-羟基-4-甲基香豆素的合成、晶体结构、抑菌活性、抗氧化活性及其与牛血清白蛋白的相互作用

设计并合成了两个新的氟代香豆素化合物8-（3-氟苯甲酰基）-7-羟基-4-甲基香豆素（3a）和8-（4-氟苯甲酰基）-7-羟基-4-甲基香豆素（3b）,其结构通过元素分析、IR和1HNMR进行了表征,通过X-射线单晶衍射测定了化合物3b的晶体结构,单晶结构分析表明,化合物3b的晶体属于单斜晶系.体外抑菌试验结果显示,目标化合物对大肠杆菌（E.coli）、枯草杆菌（B.subtilis）和金色葡萄球菌（S.aureus）有不同程度的抑制作用;体外抗氧化实验显示,目标化合物对超氧阴离子自由基（O2-·）和二苯代苦味肼基自由基（DPPH·）均有良好的清除能力;运用荧光光谱法研究了不同温度下目标化合物与牛血清白蛋白（BSA）的相互作用,结果表明,目标化合物对BSA的荧光猝灭均属于静态猝灭,相关热力学参数表明,化合物3a（H〈0,S〈0,G〈0）与BSA二者之间主要以氢键或范德华力相结合,化合物3b（H〉0,S〉0,G〈0）与BSA二者之间主要靠疏水作用力相结合;依据Fster＇s非辐射能量转移理论,求得BSA与化合物3a和化合物3b间的距离（r）分别为2.53和2.65nm,说明两个化合物与BSA之间可能发生了非辐射能量转移.     

He-N2O的从头算势能面及振转能级

采用超分子MP4方法和较大的基组计算得到了He-N₂O体系的分子间势能面,发现该势能面有3个极小值点,分别对应T形构型及两个线性He-ONN和He-NNO构型.同时采用离散变量表象方法预测了体系的振转能级,计算结果表明,MP4势能面支持5个振动束缚态.     

The reactivity of 3-methyl- and 5-methyl-1-vinylpyrazoles in free-radical polymerization

3-Methyl-l-vinylpyrazole (M3VP) and 5-methyl-1-vinylpyrazole (M5VP) were isolated as individual substances by vacuum rectification of their mixture (M3VP: M5VP 60 40). For each of them the kinetics of free-radical polymerization in MeOH were measured at low conversions. In both cases the rate of polymerization is proportional to 0.5 order with respect to the initiator (AIBN) concentration. On the other hand, a first order of reaction with respect to monomer concentration is observed only when the latter is relatively low (3M). At higher initial concentrations of monomers the order of reaction becomes less than unity. The overall rate of polymerization for M5VP was higher than for M3VP, whereas the initiation rate remained constant in the whole range of monomer concentrations and did not depend on the exact structure of the monomer. The difference in the rates of polymerization observed for M3VP and M5VP is probably connected with the difference in the key parameterk _p/k _t ^1/2 for each of the two isomers. It is concluded that the correct kinetic information about homo- and co-polymerization of M3VP and M5VP cannot be obtained without their adequate separation.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 413–415, February, 1993.     

二甲氧基嘧啶胺与金属配合物的恒容燃烧热测定

在无水乙醇中，使钴、铜、锌、锰的盐与二甲氧基嘧啶胺(AMP)反应，回流数 小时后，浓缩、冷却，抽滤，制得了6种二甲氧基嘧啶胺与钴、铜、锌、锰的固态 配合物．用化学分析和元素分析确定了它们的组成，分别为Co(AMP)_2Cl_2(1)， Cu(AMP)_2Cl_2(2)，Cu(AMP)_2(NO_3)_2(3)，Zn(AMP)_2Cl_2(4)，Mn(AMP) _2Cl_2(5)和zn(AMP)s04(6)；用IR，～1H NMR研究了他们的成键情况；用精密转动 弹热量计测定了配体及配合物的恒容燃烧热△_cU，计算了它们的标准摩尔燃烧焓 △_cH_m～θ和标准摩尔生成焓△fH_m～θ．     

A mass peak profile generation model to facilitate determination of elemental compositions of ions based on exact masses and isotopic abundances

To identify elemental compositions of ions, a mass peak profile generation model (PGM) was developed to plan data acquisitions and to interpret the data obtained by using a high resolution mass spectrometer (VG70-250SE). The PGM provides a list of all compositions possible for the exact mass of ion M and its error range from which the user selects a hypothetical composition. The PGM then plots [M + 1] and [M + 2] mass peak profiles and calculates masses and abundances of full and partial [M + 1] and [M + 2] profiles relative to the M profile. All possible compositions, calculated values for the exact masses and relative abundances, and measures of profile broadening and the shape of the [M + 2] profile are listed in a table. Pass-fail results for each of six criteria based on a comparison between table entries for the hypothetical composition and each of the other compositions are indicated. Compositions failing one or more criteria will be eliminated if the hypothetical composition is correct. The table provides assurance that all possible compositions based on the elements specified by the user have been considered. The PGM can be used to estimate the minimum resolution and number of determinations necessary to identify the correct composition by eliminating all others. As multiple determinations are made and error limits become smaller, average values are entered into the PGM to determine all compositions consistent with the data, often until only one composition remains.