由分子的价电子总数判断中心原子轨道杂化

提出了由分子的价电子总数判断中心原子轨道杂化方式的方法,探讨了该方法的理论依据,分析、归纳出了等电子分子系列中原子轨道杂化方式的周期性变化规律.     

杂化电子的离域和轨道杂化的起因

从杂化电子离域的角度讨论轨道杂化的产生,提出电子交换是轨道杂化的根本原因。同时提出分子相对离域能和绝对离域能的概念及计算方法,说明相邻原子轨道之间的电子离域对体系稳定的重要性,并用电子离域的观点对杂化分子的许多现象进行了解释。     

扩展苯基衍生物分子器件的电子输运的理论研究

通过结合杂化密度泛函和前线轨道理论与弹性散射格林函数方法研究了三种苯基衍生物分子器件的电子输运性质. 基于杂化密度泛函方法计算扩展分子电子结构的基础上, 计算了苯基衍生物三分子结的输运性质. 计算结果表明, 在低偏压下, 电流与电压呈线性变化; 分子结的电阻的对数与苯环的数目呈线性增加关系.     

图解中心原子轨道的杂化方式

借助图形方法,分析了不同常见几何构型分子中心原子轨道杂化方式的原因——与端基原子轨道的有效重叠,利用中心原子价层轨道的能量接近度的判断,决定最终可能的杂化方式。     

等性扩展基杂化轨道的构造

杂化轨道理论近来有了长足的发展,杂化轨道的构造方法主要有群论方法最大重叠方法,自然杂化轨道法和其它以分子轨道为基础构造杂化轨道的方法等。其中最大重叠杂化轨道不仅满足正交化条件而且能较定量地考虑到配体轨道的作用,因而已经得到广泛应用。本文在最大重叠原理的基础上得到了扩展基杂化轨道的解析形式。扩展基杂化轨道对一给定几何构型的分子M(X_1X_2…X_n),其中心原子M的n个杂化轨道与诸配体{X_i}形成一组方向键。M的杂化轨道(HO)和原子轨道(AO)可分别作为该分子对称操作群的表示之基。这两种不同基的表示进行约化之后,属于同一不可约表示的HO和AO是线性相     

量化方法研究分子结BEMP和TEMP的电子输运特性

通过结合杂化密度泛函和前线轨道理论与弹性散射格林函数方法研究了BE- MP(benzene-1,4-di-ethynyl-4-mercaptophenyl)和TEMP(thiophene-2,5-di-ethynyl-4- mercaptophenyl)两分子结的输运性质。基于杂化密度泛函方法计算两扩展分子电子结构的基础上,计算了两分子的输运性质．计算结果显示:电流增加来源于电极和分子轨道的共振;电导曲线呈现出平台特征．在此基础上从扩展分子A(Au-BEMP-Au)中间的苯环的旋转而引起电流减小的角度解释了负微分电阻现象．     

杂化轨道理论中等性杂化和不等性杂化的讨论

采用计算量子化学方法讨论了杂化轨道理论中等性杂化和不等性杂化,指出了不是轨道电子数而是杂化轨道成分是确定等性杂化和不等性杂化的判据。     

关于中心原子杂化轨道数的计算方法

对于HmABn型的共价分子（或离子），本文提出用公式G=V／2-3n计算中心原子A的杂化轨道数，并由此确定对应的杂化轨道类型。该方法简单、直接、有效。     

卤代硅烷分子的杂化轨道及结构与性质的关系研究

本文利用最大重迭方法,在分别考虑卤素配体的杂化及中央原子Si的d轨道杂化的基础上,计算了卤代硅烷系列分子实验构型下的杂化轨道,研究了卤代硅烷分子的NMR自旋偶合常数,IR伸缩频率和基团电负性与轨道成份的关系,较明确地反映了这类分子的化学键性质对分子谱学性质的影响。     

K/Ru(100)表面上的CO-4a_1轨道对称性确定

用同步辐射角分辨偏振紫外光电子谱对K/Ru( 10 10 )面上吸附的CO分子轨道的对称性测量发现 :结合能在 11.2eV的CO - 4a1( 4σ)分子轨道对s偏振光 (在沿〈12 10〉的入射面 )是禁戒的 .结果表明由于K的强烈影响 ,CO的分子轨道重新排列 (sp2 杂化 ) .依据选择定则和分子轨道的对称性说明 ,sp2 再杂化的CO分子吸附的桥位取向是 <12 10 >晶向     

Linear Approximation of Basis Set Orbital Exponents for Isoelectronic Series of Atoms

The orbital exponents of Slater type atomic orbitals (AOs) in isoelectronic series of atoms may be approximated by the linear dependence on the nuclear charge using a technique developed for optimization of AO basis sets in Hartree–Fock–Roothaan calculations. This approach yields the analytical Hartree–Fock wave functions for any ion in the isoelectronic atomic series without optimization of orbital exponents. The approximated linear equations for atomic orbital basis sets of B, C, O, and F in the ground state are presented as an example.     

Radial moment analysis of isovalent hybridization in N2

A radial moment analysis has been performed for the Hartree–Fock molecular orbitals of the nitrogen molecule. The objective of the analysis was to determine the extent of isovalent hybridization in even and odd sigma molecular orbitals. The radial moment analysis for the LC -SCF -AO fragments of the 2σ_g, 2σ_u, and 3σ_g molecular orbitals substantiates Mulliken's earlier conjecture concerning promotion into 3s atomic orbitals for the 3σ_g molecular orbital. The concept of free isovalent hybridization is discussed in terms of the atomic orbital shape defined by the extracted moments.     

Resolving the Unpaired‐Electron Orbital Distribution in a Stable Organic Radical by Kondo Resonance Mapping

The adsorption geometry and the electronic structure of a Blatter radical derivative on a gold surface were investigated by a combination of high‐resolution noncontact atomic force microscopy and scanning tunneling microscopy. While the hybridization with the substrate hinders direct access to the molecular states, we show that the unpaired‐electron orbital can be probed with Ångström resolution by mapping the spatial distribution of the Kondo resonance. The Blatter derivative features a peculiar delocalization of the unpaired‐electron orbital over some but not all moieties of the molecule, such that the Kondo signature can be related to the spatial fingerprint of the orbital. We observe a direct correspondence between these two quantities, including a pronounced nodal plane structure. Finally, we demonstrate that the spatial signature of the Kondo resonance also persists upon noncovalent dimerization of molecules.     

Transferability of modified atomic orbitals

The modified atomic orbital basis set determined for molecular orbital calculations on a given molecule is shown to be transferable to other molecules. This transferability is examined using the modified atomic orbital basis set determined for the carbon atom in methane for calculations on ethane, propane, butane, cyclohexane, acetylene, ethylene and benzene.     

Ab initio calculation of maximum bond order hybrid orbitals

Summary The maximum bond order hybrid orbital (MBOHO) procedure is tested onab initio level by use of the density matrix in Löwdin orthogonalized atomic orbital basis. The direct MBOHO calculation based on the whole density matrix includes also the hybridization of the inner atomic orbitals, and the MBOHO calculation based on the valence orbital part of the density matrix considers only the hybridization of the valence atomic orbitals. The concrete MBOHO calculations based on theab initio calculation with STO-3G basis show that the components of the s atomic orbitals in MBOHOs and the maximum bond orders obtained from the two kinds of MBOHO calculations are very close to each other, and that the two kinds of MBOHOs all have the excellent correlativity with the nuclear spin-spin coupling constants.The project supported by National Natural Science Foundation of China and the Excellent Young University Teacher's Foundation of State Education Commission of China.     

Theoretical approach to the molecular structure,chemical reactivity,molecular orbital analysis,spectroscopic properties (IR,UV, NMR), and NBO analysis of deferiprone

In this investigation, the structural, electronic properties, ¹³C and ¹H NMR parameters and the first hyperpolarizability of deferiprone are computed in the gas phase and various solvents at the M062X/6-311++G(d,p) level of theory. The solvent effect on the structural parameters, frontier orbital energies, ¹³C and ¹H NMR parameters is also explored based on a polarizable continuum model. These consequences specify that the polarity of solvents affects the structures and spectroscopic properties of deferiprone. ¹H and ¹³C NMR chemical shifts are evaluated by employing the gauge-invariant atomic orbital method. NBO analysis is exploited to examine the hybridization of atoms, atomic charges, and their second order stabilization energy within the molecule.     

A new one-electron model for extended Hückel type molecular orbital calculations

A new form of Coulomb and resonance integrals for extended Hückel type molecular orbital calculations was derived. In this model an electron moving in a molecule, when it stays in the neighborhood of the center of an atom in the molecule, sees the potential of the corresponding isolated atom. Compared with the well-known forms of Coulomb and resonance integrals, each integral derived from this model considers the influences from all atoms in the molecule, and includes the concept of atomic cell. The similarities of this model to other extended Hückel type formulations are also examined.     

Cu(001)表面CO吸附单层结构和电子态的第一性原理研究

用密度泛函理论(DFT)研究了Cu(001)表面CO吸附单层的表面性质. 总能计算结果表明, 顶位结构总能最低, 相应位置的CO分子吸附能最大. 谷位吸附结构的衬底原子层间距相对于清洁表面的膨胀量约为10%, 从而导致了谷位吸附的不稳定性. 在顶位、桥位和谷位三个吸附结构中, C和Cu原子之间的距离dC-Cu分别为0.1868、0.1975和0.2231 nm, 对应的CO分子键长为0.1154、0.1165 和0.1175 nm. 计算了CO分子的态密度(DOS). 结果表明, 衬底与分子的作用主要是分子和金属轨道的杂化. 在吸附过程中, 电荷主要从碳原子的s轨道向p轨道转移. 在顶位、桥位和谷位吸附结构中, 每个碳原子内电荷的转移量分别为0.45e、0.54e 和0.55e. 衬底向吸附分子的电荷转移量不大, CO 吸附分子层为一绝缘层.     

Interaction of metallic nanoparticles with a biologically active molecule, dopamine

We present the results of first-principles molecular orbital calculations describing the interaction of metallic nanoparticles, represented by Mn(13), Ag(13), and Al(13) atomic clusters, with a biologically active molecule, dopamine. The interaction strength, determined in terms of the nanoparticle-molecule complex binding energy, is found to be higher for Mn than either Ag or Al and can be explained in terms of the degree of the hybridization of the (metal) atomic orbitals with the molecular orbitals in the complex. Furthermore, smaller interaction strength of these metallic nanoparticles with water compared to that with dopamine predicts the preference of forming a complex of dopamine with the metallic nanoparticles in the aqueous solution. The calculated results may therefore suggest that the presence of these metallic nanoparticles could induce different levels of dopamine depletion in solution.