p型Se的电沉积及其转化为n型CdSe的机理研究

利用线性电位扫描光伏安法等技术研究钛基体上Se半导体薄膜的电化学形成及转化过程.实验结果表明,在H_2SeO_3溶液中进行电沉积可获得p型Se薄膜,它可在酸性CdSO_4溶液中阴极转化为n型CdSe.讨论了Se的电沉积动力学及其转化为CdSe的可能机理.所述原理可望用于p-n异质结的电化学制备.     

Potential energy surface for linear triatomic molecules: An algebraic method

Recently, we proposed a new transformation between the angle of canonical coordinates and the bond angle to describe the bending motion in Potential Energy Surfaces (PES) of bent triatomic molecules. In this work we extend the transformation to include linear triatomic molecules. Results for the linear triatomic molecule N₂O are reported.     

受限混合物溶剂中胶粒的耗尽势及吸附稳定性

基于密度泛函理论和Yvon-Born-Green方程得到了胶粒耗尽势的表达式.采用密度泛函理论计算了单壁附近和平行狭缝中的混合物溶剂中胶粒的耗尽势及其在单壁处的吸附稳定性.研究结果表明,不同溶剂组分的体积分数和粒子尺寸比等因素对胶粒耗尽势的强度、力程和周期均可产生显著影响,胶粒在单壁附近的吸附稳定性与溶剂粒子尺寸比和体积分数密切相关.此外,对受限于平行狭缝的胶体悬浮液,胶粒的耗尽势阱还可随粒子尺寸比和缝宽呈振荡趋势变化.     

Time-dependent mixing and demixing processes in binary lipid monolayers studied by mixed and separate spreading using film pressure and film potential measurements

Using both spreading techniques — mixed spreading and separate spreading- and, simultaneously, film pressure and film potential measurements, the mixing behavior of the following five binary systems was investigated and compared: 1) system 1,2-dilauroyl-phosphatidylethanolamine/cholesterol; 2) system 1,2-dimyristoyl-phosphatidylethanolamine/cholesterol; 3) system 1,2-dipalmitoyl-phosphatidylethanolamine/cholesterol; 4) system Na-eicosyl sulphate/hexadecanol; 5) system phosphatidic acid/1,2-dimyristoyl-phosphatidylethanolamine.Analyzing the time and concentration dependence of the /a isotherms and v/a isotherms (^s = film pressure, v ^s potential,a=average area per molecule in mixed films in the monolayers) of the binary monolayers it can be concluded that the components of the binary systems 1–4 are complete miscible in the monolayers. On the other hand the components of the system 5 are probably partially miscible only.     

COSMIC(90): An improved molecular mechanics treatment of hydrocarbons and conjugated systems

Summary Four modifications to the COSMIC molecular mechanics force field are described, which greatly increase both its versatility and the accuracy of calculated conformational energies. The Hill non-bonded van der Waals potential function has been replaced by a two-parameter Morse curve and a new H-H potential, similar to that in MM3, incorporated. Hydrocarbon energies in particular are much improved.A simple iterative Hückel pi-electron molecular orbital calculation allows modelling of conjugated systems. Calculated bond lengths and rotational barriers for a series of conjugated hydrocarbons and nitrogen heterocycles are shown to be as accurate as those determined by the MM2 SCF method.Explicit hydrogen-bonding potentials for H-bond acceptor-donor atom pairs have been included to give better hydrogen bond energies and lengths. The van der Waals radii of protonic hydrogens are reduced to 0.5 Å and the energy well depth is increased to 1.0 kcal mol^-1.Two new general atom types, N⁺ _sp ² and O^- _sp ³ , have been introduced which allow a wide variety of charged conjugated systems to be studied. A minimum of parameterisation is required, as the new types are easily included in the Hückel scheme which automatically adjusts bond and torsional parameters according to the defined bond-order relationships.     

Ab initio molecular orbital study of potential energy surface for the H2NO(B1)→NO(Π)+H2 reaction

The mechanism of the H₂NO(²B₁)→NO(²Π)+H₂ reaction has been examined using ab initio molecular orbital methods. Ground-state and first-excited-state potential surfaces were plotted at the FOCI/cc-pVTZ level of theory as functions of two appropriate internal degrees of freedom. A conical intersection was found on the C_s pathway that is symmetric with respect to the plane perpendicular to the molecular plane of C_2v H₂NO(²B₁). It is therefore considered that trajectories that start from H₂NO(²B₁) towards the product region detour around the conical intersection, pass through the neighborhood of the transition state that is located at the saddle point on the C_s pathway, and finally reach the products, NO(²Π)+H₂. Thus we can explain the mechanism of the H₂NO(²B₁)→NO(²Π)+H₂ reaction, which has remained unclear to date.     

Determination of the correlation effects in molecules using the complete error potential

Summary The complete error potential is used for the study of the correlation of molecules. The correlation can be seen as a relaxation of the electrons and a relaxation of the nuclei. From the Fermi sea, the electronic relaxation gives rise to a partial excitation of each orbital which collectively generates a linear, a surface or a volume pressure; the resulting forces acting on the nuclei are defined in a general theory of the intramolecular forces. H₃, H ₃ ⁺ , the diatoms and the hydrid of the first nine elements are taken as examples.     

C_4S_4~(m-)(m=0,1,2,3,4)的从头算研究2.成键状况、电离势和振动频率

在ＲＨＦ（基离子在ＵＨＦ）／６－３１Ｇ,６－３１Ｇ＊和６－３１＋Ｇ水平用从头算和Ｂｏｙｓ定域化方法计算了Ｃ４Ｓ４ｍ－（ｍ＝０,１,２,３,４）的电子结构、电离势和定域化分子轨道。讨论了其成键特征和电离势与ΔＥＳＣＦ的关系。在６－３１Ｇ水平用ａｂｉｎｉｔｉｏ解析方法计算它们的谐振动频率。电子结构计算结果和Ｂｏｙｓ定域化分子轨道及振动分析结果与优化的平衡几何和相对稳定性相一致     

分子力场进展

分子力学（简称ＭＭ）是近年来化学家常用的一种计算方法。与量子力学从头计算和半经验方法相比，用分子力学处理大分子可以大大节省计算时间，而且，在大多数情况下，用分子力学方法计算得到的分子几何构型参数与实验值之间的差值可在实验误差范围之内。所以，分子力学是研究生物化学体系的有效和可行的手段。分子力学的核心是分子力场。本文介绍了分子力场的量子力学背景、分子力场和光谱力场之间的关系。分子力场的一般形式、分力     

Molecular simulation of electrolytes in nanopores

Behaviour of electrolytes confined in cylindrical and slit pores are studied by computer simulations at the molecular level. Previous equilibrium and structural properties obtained by Monte Carlo techniques using the restrictive primitive model are discussed. Transport properties are calculated by the canonical molecular dynamics technique for ions with Lennard–Jones cores. Assuming an external electric potential, the chemical potential of individual ions can be balanced without the need for a grand canonical procedure. The mobility of the counterion is affected by the surface charge density. At a high surface charge, the mean square axial displacement of the counterion calculated is lower than the bulk value due to its high concentration near the charged wall.