有机同系物密度递变规律

有机同系物密度递变规律曹晨忠（湘潭师范学院化学系，湘潭４１１１００）密度是有机化合物的一个基本物理性质，人们一直在探求有机化合物的结构与密度的关系。梅平￣［１］等曾用拓扑指数讨论直链饱和烃取代衍生物的密度变化，结果与实验的符合程度较好。然而文献［１］...     

基于睡眠规律的管制员认知能力分析

为了更加准确评估管制员工作状态,针对管制员认知能力评估问题,采用贝叶斯网络模型,提出了一种基于睡眠规律的分析方法.首先归纳了评价睡眠规律的主要因素,并采用PVT反应时间量化管制员的认知能力水平;然后根据先验知识构建了贝叶斯网络模型,在实验统计与模糊集理论的基础上得到条件概率表CPT,参数学习更新,并计算相关系数确定了关键因素;最后通过实际案例分析,预测了管制员认知水平,验证了评估的可行性与合理性.实验结果表明该分析方法能够根据睡眠规律对管制员值班前的认知能力进行准确的评估,降低了人为因素的安全隐患,增强了人员岗前管理的主动性.     

LaC_3~n(n=-1,0,+1)分子簇的理论研究(英文)

用密度泛函方法研究了ＬａＣ３ｎ（ｎ＝－１，０，＋１）分子簇的结构和稳定性，对这个四原子体系，提出了５种可能构型，其中３种具有Ｃ２ｖ对称性，２种为Ｃ∞ｖ对称性．在Ｃ２ｖ对称性结构中，其中１个为Ｌａ接在弯曲的Ｃ３链上，第２个是Ｌａ通过２个键与Ｃ３环相链，第３个是Ｌａ通过１个键与Ｃ３环相连；在Ｃ∞ｖ对称性中，第１个Ｌａ接在Ｃ３链的一端，而在第２个构型中，Ｌａ被插入在Ｃ３链中．结果表明，环状结构当Ｌａ接在弯曲的Ｃ３链上的是局域极小值并且最稳定     

用DFT方法对次磷酸根吸附在Ni(111)和Ag(111)表面的比较性研究

用密度泛函理论在B3LYP/6-31++G(d,p)水平研究了次磷酸根(H2PO2-) 在Ni(111)和Ag(111)表面吸附的表面结构和电子特性。最稳定的结构是H2PO2-中的两个P－O键朝向基底表面。Mulliken布居分析结果表明，由于电子构型的微小差别，导致了H2PO2- 在Ni(111)表面上的吸附能远大于在Ag(111)表面上吸附能，Ni(111)表面上的电子给予与反馈数量远大于在Ag(111)表面上的电子给予与反馈数量。与吸附在Ag(111)表面上相比较，当H2PO2- 吸附在Ni(111)表面上时有更多的负电荷转移到基底，且P原子上有更多的正电荷。这意味着吸附在Ni(111)表面上的H2PO2-更容易被像OH-一样的亲核试剂进攻。因此，吸附在Ni(111)表面上的H2PO2-比吸附在Ag(111)表面上的H2PO2-更容易被氧化。这些结果表明对于H2PO2-的氧化，银表面不具有活化作用而镍表面则具有活化作用。     

离子液体BMIBF4性质的研究

用最大气泡法和韦氏天平法, 在278.15～343.15 K范围内测定了离子液体BMIBF₄的表面张力和密度; 讨论了这个离子液体的体积性质和表面性质; 根据离子个头大又极不对称的特点, 提出了离子液体的空隙模型. 根据空隙模型计算的离子液体恒压热膨胀系数与实验值相比, 偏差在10%左右.     

Densities,Ultrasonic Speeds,Viscosities and Refractive Indices of Binary Mixtures of Benzene with Benzyl Alcohol,Benzonitrile, Benzoyl Chloride and Chlorobenzene at 303.15 K

Densities,ρ, ultrasonic speeds, u, viscosities,η, and refractive indices, n, of pure benzene, benzyl alcohol (BA), benzonitrile (BN), benzoyl chloride (BC), chlorobenzene (CB) and their thirty six binary mixtures, with benzene as common component, were measured at 303.15 K over the entire mole fraction range. From these experimental data the values of deviations in ultrasonic speed, △u, isentropic compressibility, △k_s,excess acoustic impedance, Z^E, deviation in viscosity, Dh, and excess Gibbs free energy of activation of viscous flow, G^*E, and partial molar isentropic compressibility, Kφ,2⁰ of BA, BN, BC and CB in benzene were computed. The variation of these derived functions with composition of the mixtures suggested the increased cohesion (molecular order) in the solution and that interaction (A-B)＞(A-A) or (B-B).Moreover, theoretical prediction of ultrasonic speed, viscosity and refractive index of all the four binary mixtures was made on the basis of empirical and semi-empirical relations by using the experimental values of the pure components. Comparison of theoretical results with the experimental values was made in order to assess the suitability of these relations in reproducing the experimental values of u, η and n. Also, molecular radii of pure liquids and the average molecular radii of binary mixtures were evaluated using the corresponding refractive indices of pure liquids and binary mixtures. The average molecular radii of binary mixtures were found to be additive with respect to mole fraction of the pure component.     

NH2(～X2B1)与CH4反应机理的理论研究

在密度泛函理论B3LYP／6－311G^*水平下，研究了NH2与CH4的反应机理。通过振动频率和内禀反应坐标（IRC）分析，对反应过渡态进行了确认。在QCISD（T）／6－311G^*水平下进行了单点能计算，并进行了零点能校正，结果表明，反应NH2＋CH4→N3＋CH3是主要的反应通道。     

改进Hückel模型变分法与同系线性规律

一、引言同系线性规律可以表示为:P=a+bF(N)其中P是同系化合物的物理化学性质,a、b 是常数,F(N)是同系线性函数,N=n+t,n 是同系序数,t 是端基当量。人们在探求 F(N)方面做了较多的工作,最近的有以下几个:     

Molecular Dynamics Simulation of the Self-assembled Monolayers of 1-Adamantanethiolate and Its Derivatives on Au（111） Surfaces

The self-assembled monolayers （SAMs） of 1-adamantanethiolate and its derivatives on Au（111） surface were investigated. Density functional theory （DFT） calculation indicates that the most stable configuration for absorption is at the face centered cubic （fcc）-bridge site. Canonical ensemble molecular dynamics （MD） simulations were carried out to study the structures and energies of the SAMs. The ordered structures of the SAMs were analyzed by means of radial distribution function and the relative stability of the SAMs was compared. It was concluded by the comparison of various contributions to the SAM formation energy that the formation of the SAMs was determined by the intermolecular nonbonding interaction and the chemical bonding interaction of sulfur and gold.