Dynamics and mode-selected reaction of NCO+H_2→HNCO+H

The reaction path of the reaction NCO+H2→HNCO + H has been traced by Fukui's theory and the ab initio method. On this basis, the dynamical properties along the reaction path, canonical variational theory (CVT) rate constants and vibrational-mode-selected rate constants have been computed. The results show that the effect of the electron correlation energy on the activation barrier is large, and tiros the correction by MP4 method is effective; the results also show that the recrossing and tunneling effects exist, and thus the corrections by the variational transition state theory (VTST) and the small curvature (SC) approximation method are also effective. In the reaction, the coupling and energy transfer between mode 8(7) and reaction path are strong, so the rate is effectively enhanced while these modes, especially H2 stretching, are vibrationally excited.     

[CH3ONO2]H+正离子与R-OH型分子相互作用的DFT研究

用密度泛函(DFT)(B_³LYP) 方法,在6-31G(d,p)基组水平上优化了两种质子化的硝酸甲酯异构体几何构型和能量,研究了异构体与H₂O、CH₃OH等分子之间的氢键的相互作用,提出了氢键超分子复合物的两种平面结构。研究发现在酯位质子化异构体的相对稳定性高于在硝氧位质子化的异构体。但当异构体在液相中与ROH类分子发生分子间相互作用后这一顺序发生了反转,说明了该体系中的分子间相互作用对异构体较强的影响。     

Ab initio study on the mechanism of rhodium-complex- catalyzed carbonylation of methanol to acetic acid

The whole catalytic cycle of the carbonylation of methanol to acetic acid catalyzed by Rh complex is theoretically studied. All structural geometries of reactant, intermediates, transition states and product are optimized at HF/LANL2DZ level under the ECP approximation. The potential energy profiles for elementary reactions of carbonylation are calculated respectively. The transition states are further confirmed by having one and only one imaginary vibrational frequency. The results indicate that the activation energy values of CH3I oxidative addition, carbonyl insertion and CH3COI reductive elimination fundamental steps are 216.03, 128.10 and 126.55 kJ/mol, respectively; and that the CH3I oxidative addition step is predicted to be the rate-determining one.     

CH3NO2+X(X=H,OH, CH3, CH2[^3B1], O[^3P])→CH2NO2+XH吸氢反应过渡态 结 构和反应位垒的DFT计算研究

采用DFT(B3LYP)方法,分别在6-311g(d,p),6-311++g(d,p)和自洽相关基组cc-pVIZ水平上优化了基态硝基甲烷和自由基H,OH,CH3,CH2[^3B1]以及O[^3P]等发生吸氢反应时的过渡态结构,并计算了反应的位垒。研究表明,对同一反应,不同基组下优化得到的过渡态几何结构基本一致;反应位垒数值的大小也基本接近,经校正,硝基甲烷同自由基反应位垒的理论计算值同实验结果基本吻合。     

结构化学教学研究(Ⅰ)——以H_2体系为例对单行列式波函数LCAO-MO理论适用性的讨论

讨论了H_2体系的单行列式波函数在体系平衡点和远离平衡点的性质。阐述了单行列式的LCAO-MO理论方法的适用性。     

指数和与特征和的混合均值

本文利用三角和估计及其特征和的性质研究一类二项指数和与多项式特征和的混合均值的计算问题,并给出两个有趣的计算公式.     

动态VaR约束下带阀值分红的保险最优投资

考虑受动态VaR约束时带阀值分红策略的保险公司最优投资策略问题,假定保险公司盈余服从扩散过程,在分红总量现值的期望最大化准则下,使用动态规划原理建立了受动态Va R约束的保险公司最优投资组合选择模型,通过求解HJB方程得到最优金融决策的显示解。