Force Constants and Bond Orders of Nitrogen Bonds

The force constants and the corresponding bond orders of nitrogen bonds have been calculated from the vibrational spectra (infrared and Raman spectra) of a great number of nitrogen compounds. Plotting the maximum bond order of stable nitrogen bonds against the sum of Pauling's electronegativities of the bonding partners (Σx) leads to one continuous curve for the N? X bonds where X represents elements of the first and the second short period of the periodic table. Furthermore, when the bonds formed between these elements are arranged in a coordinate system in such a way that the position of each bond is determined by the difference between the electronegativities of the bonding partners (Δx along the ordinate) and the sum of the electronegativities of the bonding partners (Σx along the abscissa), the bonding partners capable of forming multiple bonds all lie within a closed domain, where their position can be correlated with their polymerizability and other reactivities of the multiple bonds. Also discussed are the orders of bonds between nitrogen and some transition elements. In an appendix, the present methods used to calculate force constants and bond orders are surveyed.     

Comparison of the Hartree-Fock,Møller-Plesset,and Hartree-Fock-Slater method with respect to electrostatic properties of small molecules

Summary The results of various quantum chemical calculations, the Hartree-Fock (HF) method, the Møller-Plesset perturbation theory (MP2), and the Hartree-Fock-Slater (HFS) method are compared. Atomic charges, dipole moments, topological properties of the electron density distribution and polarizabilities, and first hyperpolarizabilities are calculated. Atomic charges obtained with the HFS method are found to be very close to those calculated with the MP2 method, from which we conclude that the HFS method describes to some extent electron correlation effects. Performing an MP2 calculation after an HF calculation improves the molecular dipole moments considerably, yielding values close to the experimental ones. HFS calculations are computationally less demanding than MP2 and yield comparable results for the electron density distributions, dipole moments and polarizabilities.     

On the theory of solvent effects

A simple electrostatic analysis is given of the virtual charge (solvaton) model to represent the environment effect on the electronic wave function of a solute immersed in a polarizable surrounding. New features of this model are found. The classical aspects are discussed and secondly the quantal implications are considered. A correct Hartree-Fock-like operator is derived which represents an electron in a molecular orbital subjected to the average effect of the other electrons and to the reaction field produced by the virtual charges on the atomic centers.A general formalism based on the preceding model is presented in appendix. The final equations have a form similar to Newton's equation to represent a solvated electron. Unlike some other theories in this field, there is no cut-off involved in the evaluation of the molecular integrals.     

The Hellmann-Feynman theorem applied to long-range forces

The relations between the Hellmann-Feynman forces in laboratory fixed (L-) and relative (R-) coordinate systems are clarified. In the usualL-coordinate system, the force is interpreted as force on nucleus, while in theR-coordinate system, it means force on whole particles consisting of the electrons and nuclei of each interacting subsystem. From a perturbation theoretical viewpoint, the concept of the force on whole particles correctly corresponds to the perturbation energy and is superior to the force on the nucleus.     

基于改进断裂点理论的机场吸引范围界定

合理界定机场吸引范围,是构建坚固民航运输网络的关键环节。现有的机场吸引范围界定方法,很少考虑与其衔接的地面交通网络,以及旅客出行偏好的影响。为提高机场吸引范围的实用性,本文以城市断裂点理论为基础,对其中的重要参数予以改进。首先,以综合交通运输为背景,指出发达的公路和铁路运输网络对民用机场具有很大的竞争与促进作用,并提出以地面交通出行时间为量化标准的吸引范围界定方法。然后,为分析旅客出行偏好的行为机理,针对于与机场衔接的地面交通网络来建立离散选择模型。其次,将研究区域的机场所在城市看作是一个整体,运用专家评价法和熵权法综合确定机场的吸引规模,并通过机场吞吐量与城市对外出行总量针对机场规模进行修正。最后,通过算例验证改进模型的实际可操作性,为确定多机场系统吸引范围界定提供新的思路和方法。     

盾构隧道围岩与衬砌协同作用纵向位移计算法

盾构机掘进过程中,千斤顶顶进力的不均匀引起的纵向位移是管片间初始错台的主要原因之一;基于Timoshenko梁理论的隧道纵向位移计算方法,未能考虑隧道开挖后围岩卸载破坏的变形特征及围岩与衬砌结构的协同作用效应,预测误差较大。建立了考虑围岩卸载扩容效应的等效地基抗力系数计算方法,提出了能考虑螺栓个数的等效抗剪刚度计算公式,建立一种基于Timoshenko梁理论的改进管片拼装式隧道纵向位移理论计算方法。实际工程案例分析表明：考虑围岩开挖卸载过程中围岩的非线性体积相关塑性变形（即扩容效应）更合理;考虑壁后注浆液固化过程的时效性,采用改进的滑移边界条件计算的纵向位移最大值是传统的固定端边界的计算值的2.3倍,边界条件对计算结果影响较大,本文计算方法更符合实际情况,也更安全。     

具有不定位势Kirchhoff型Schrödinger-Bopp-Podolsky系统解的存在性

研究Kirchhoff型Schrödinger-Bopp-Podolsky系统,考虑位势函数V不定的情况。此时Schrödinger算子-Δ+V具有有限维负空间。利用Morse理论,得到Kirchhoff型Schrödinger-Bopp-Podolsky系统非平凡解的存在性。     

睡莲科植物酯酶同功酶的数量分类研究

采用垂直平板聚丙烯酰胺凝胶盘状电泳技术,对国内睡莲科植物（包括６个属的６个代表种及３个品种）的叶片进行了酯酶同功酶的测定,初步结果表明被测植物均有各自稳定的酯酶酶谱．运用数量分类学方法对被测植物进行聚类,其中白睡莲与其派生的红睡莲和黄睡莲２品种聚为一类,南芡与北芡亦聚为一类,而此２类与萍蓬草、莲、莼菜和王莲的亲缘关系较远,且后４种植物之间亲缘关系亦远．该结果与由过氧化物同功酶酶谱的分析结果基本相似．     

An experiment to test an explanation of a possible violation of quantum theory

An experiment to test a possible explanation of the Schmidt backwards causation results is suggested. The experiment might distinguish between many- and one- world interpretations of quantum theory.     

Moment closure hierarchies for kinetic theories

This paper presents a systematicnonperturbative derivation of a hierarchy of closed systems of moment equations corresponding to any classical kinetic theory. The first member of the hierarchy is the Euler system, which is based on Maxwellian velocity distributions, while the second member is based on nonisotropic Gaussian velocity distributions. The closure proceeds in two steps. The first ensures that every member of the hierarchy is hyperbolic, has an entropy, and formally recovers the Euler limit. The second involves modifying the collisional terms so that members of the hierarchy beyound the second also recover the correct Navier-Stokes behavior. This is achieved through the introduction of a generalization of the BGK collision operator. The simplest such system in three spatial dimensions is a 14-moment closure, which also recovers the behavior of the Grad 13-moment system when the velocity distributions lie near local Maxwellians. The closure procedure can be applied to a general class of kinetic theories.