第二过渡金属双核物的从头算研究 Ⅱ:四羟基桥联双核物的化学键

本文用从头计算方法讨论第二过渡金属M2(O2CR)4L2体系的电子结构(采用有效核芯势价基), 计算结果表明, 金属原子M-M间除了定域的σ,π键以外, 还有一个离域的大π键, 大π键由金属与配体四羟基组成, 这种电子结构较好地解释了多年来波谱实验提出的疑问。     

量子化学从头计算法研究C~7~6的分子静电势

在MNDO-PM3方法优化的分子结构基础上, 用Hartree-Fock/6-31G从头计算法研究了D2点群手性C~7~6稳定结构的分子静电势, 获得了过C~7~6对称中心的三个正交平面XY, XZ和YZ上的平面静电势图和径向静电势图, 并与C~6~0和C~7~0做了对比分析。     

稠环芳烃系列化合物化学位移的计算 IV.^1H化学位移加合性规律的量子力学基础

Based on a starting point of the McWeeny Huckel-London perturbation theory approximation, a formula similar to the fourmula of additivity rule for the calculations of the chemical shifts of condensed aromatic hydrocarbons has been derived. The quantum mechanical basis of additivity rule is thus indicated by this formula. It is shown that by using the concept of aromatic shift and sigma ratio, this method for calculation of proton chemical shifts has the virtues of definite physical meaning and simple calculation. It can also be extended to the calculation of the proton chemical shifts of substituents fr the molecules of this series.     

分光光度法同时测定两个干扰组份的研究 I.多波长数据线性回归法及其应用于同时测定微量锰和锌的探讨

In this paper, a linear regression method of multiwavelength data is proposed. The method, based on the difference of molar absorptivity between two coloured chelates at murti-wavelengths, can be applied to simultaneous spectrophotometric determination of two-interfering-component systems in the visible region. As an example, the availability as well as the optimum condition for simultaneous determination of Mn and Zn with 5-Br-PADAP in the presence of nonionic surfactant Triton X-100 have been studied. Measure the absorbance at 15 wavelengths over the range of 540-584 nm and treat the data with the suggested method, the linear correlation coefficients (γ) are found to be 0.998 in the synthetic mixtures containing microamounts of Mn and Zn with the concentration ratio from 1:10 to 10:1. The recoveries of both elements are 95-120% with the relative standard deviations (N=5) less than 17%. the method has been successfully used for direct determination of Mn and Zn in tap water. The new method proposed in this work is simple, fast and can be used for the analysis of two-interfering-component systems.     

单Slater行列式波函数的能量表示式的简化及其应用

本文简化了单Slater行列式型波函数的电子总能量表达式, 对闭壳层体系. 利用该式进行从头计算, 可以不涉及分子轨道系数、密度矩阵等概念, 数学模型比较简单, 能够保证计算过程有选择地收剑到指定的激发态. 并能迅速判断旋转的角度. 但因为需要进行四维变换, 限制了对大基组分子的应用. 本文对开壳层体系自旋非限制的Hartree-Fork计算, 也推导了类似的公式.     

STUDY ON CASTOR OIL POLYURETHANE/POLY (METHYL METHACRYLATE) AB CROSSLINKED POLYMERS

Castor oil polyurethane/poly(methyl methacrylate) AB crosslinked polymers (ABCP) were synthesized by free radical copolymerization of MMA and vinyl-terminated castor oil polyurethane which was obtained from isocyanate-terminated castor oil polyurethane and hydroxyethyl methacrylate The mechanical properties, transition and relaxation, as well as compatibility and morphology of the ABCP were investigated by changing the component. The results show that the ABCP is a semicompatible system and the compatibility of the two components decreases with increasing content of the hard segment. The mechanical and damping properties of the ABCP are obviously superior to that of their homopolymers. The damping value is mainly controlled by cross[ink density of the ABCP but the T-g value by component.     

UPS和功函数研究氧在电解银上的吸附

本文报导了用紫外光电子能谱(UPS), 热脱附(TDS)和表面功函数连续测量等手段对氧与电解银表面相互作用过程中的电荷传递, 成键以及吸附动力学等研究的实验结果。     

Acid chloride‐functionalized hyperbranched polyester for facile and quantitative chain‐end modification: One‐pot synthesis and structure characterization

Carboxylic acid chloride end‐functionalized all‐aromatic hyperbranched polyesters were prepared from the bulk polycondensation of the AB₂ monomer 5‐(trimethylsiloxy)isophthaloyl dichloride. The acid chloride end functionality of the hyperbranched polyester was modified in situ with methanol and yielded methyl ester ends in a one‐pot process. Chain‐end functionalization and esterification were quantitative according to both potentiometric titration and ¹H NMR analysis. The signals of ¹H and ¹³C NMR spectra of the esterified hyperbranched polyester were fully assigned from model compounds of the focal, linear, dendritic, and terminal units. The degree of branching and molecular weight averages measured by ¹H and ¹³C NMR spectroscopy and multidetector size exclusion chromatography increased systematically with increasing polymerization temperatures between 80 and 200 °C. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2855–2867, 2002     

二氮双环阳离子游离基中N,N'-三电子键

用从头算HF/3-21+G^*优化了二氮双环[m,n,l]游离基阳离子(m,n,l≥2～5)。分子[4,4,4]和[2,2,2]^+.,[3,3,3]^+.,[4,4,4]^+.游离基阳离子的优势构型有D3对称性,而其它游离基阳离子的优势构型为非对称性。通过比较这些阳离子几何构型,HOMO和NHOMO(即NextHOMO和HOMO-1),和由MNDO计算确定的原子对作用能,表明当二氮双环游离基阳离子的桥链(CH2)n的n≥3时,桥头氮原子通过空间相互用用形成了一个弱的N,N'-三电子σ键。形成的三电子键强度不随环的扩大而增强。而三电子键强度被两个因素影响：一个是桥头氮原子间的p轨道重叠的取向;另一个是它们相应p轨道成分。     

An efficient pseudo‐spectral Legendre–Galerkin method for solving a nonlinear partial integro‐differential equation arising in population dynamics

The pseudo‐spectral Legendre–Galerkin method (PS‐LGM) is applied to solve a nonlinear partial integro‐differential equation arising in population dynamics. This equation is a competition model in which similar individuals are competing for the same resources. It is a kind of reaction–diffusion equation with integral term corresponding to nonlocal consumption of resources. The proposed method is based on the Legendre–Galerkin formulation for the linear terms and interpolation operator at the Chebyshev–Gauss–Lobatto (CGL) points for the nonlinear terms. Also, the integral term, which is a kind of convolution, is directly computed by a fast and accurate method based on CGL interpolation operator, and thus, the use of any quadrature formula in its computation is avoided. The main difference of the PS‐LGM presented in the current paper with the classic LGM is in treating the nonlinear terms and imposing boundary conditions. Indeed, in the PS‐LGM, the nonlinear terms are efficiently handled using the CGL points, and also the boundary conditions are imposed strongly as collocation methods. Combination of the PS‐LGM with a semi‐implicit time integration method such as second‐order backward differentiation formula and Adams‐Bashforth method leads to reducing the complexity of computations and obtaining a linear algebraic system of equations with banded coefficient matrix. The desired equation is considered on one and two‐dimensional spatial domains. Efficiency, accuracy, and convergence of the proposed method are demonstrated numerically in both cases. Copyright © 2012 John Wiley & Sons, Ltd.