共查询到17条相似文献,搜索用时 109 毫秒
1.
以椅式环己烷为例,介绍了如何应用分子模拟软件制作含有分子对称元素的VRML模型的过程。利用VRML的交互性可以帮助学生直观地掌握分子的三维结构以及对称元素的分布,切实提高了分子对称性的教学效果。 相似文献
2.
3.
根据群论,阐述了对称性匹配的原子轨道不仅可以组成成键分子轨道,同样可组成反键分子轨道,否定了反键分子轨道是由对称性不匹配原子轨道组合的观点 相似文献
4.
5.
6.
7.
本文是作者近年来研究的最大重迭对称性分子轨道(MOSMO)模型的基本理论思想、方法和特点及其发展的一个概要性综述。 相似文献
8.
计算机分子模拟技术在科技发达国家正越来越广泛地用于科研生产、教学的各个相关领域,它不仅使分子、原子等微观粒子的结构形象化、可视化[1],而且通过结构信息分析、模拟、数据处理一体化技术,从微观角度揭示结构与性质的关系,预示各种化学现象、生命现象、物理现象的模型,解释物质的微观至宏观的各种性质,进行各种材料如合金、陶瓷的优化与设计,药物的合理设计等等。这些应用反过来又推动了计算机分子模拟技术的发展。一些科研机构、公司不断结合国际上有关先进技术、信息资料推出了一些优秀的软件产品,分子模拟软件Insig… 相似文献
9.
通过图示和矩阵两方面来阐述独立的对称元素和非独立的对称元素之间的区别与联系,利用比较法帮助读者正确理解独立对称元素的内涵。 相似文献
10.
以实例介绍了用轨道绘制软件OrbitalViewer制作原子、分子轨道 3D图形和VRML动画的方法 ,以及这些素材在网络课件和PowerPoint演示中的显示与播放方法 相似文献
11.
一般来说,点群理论认为M(o)bius带环分子最高的对称性只能是C2.本文讨论了由18个苯环组成的环并苯的异构体分子,包括柱面的Hückel型分子(HC-[18])和扭转180°的M(o)bius带环分子(MC-[18]).结果表明除了点对称性外,M(o)bius带环分子还存在一种可称为环面螺旋旋转(TSR)变换的对称性,为此还引用了环面正交曲线坐标系.此外,还讨论了这些分子关于TSR对称性匹配的原子集和原子轨道(AO)集.根据TSR对称性的循环群特征,可以建立此类群的不可约表示及有关特征标.这类分子的分子轨道(MO)关于TSR群的不可约表示是纯的,然而所含的相应的原子轨道对称性匹配的线性组合(SALC-AO)成分可以是多种的. 相似文献
12.
13.
David Casanova Pere Alemany Santiago Alvarez 《Journal of computational chemistry》2010,31(13):2389-2404
In this communication we define electronic symmetry operation and symmetry group measures, eSOM and eSGM, respectively, develop the basic algorithms to obtain them, and give some examples of the possible applications of these new computational tools. These new symmetry measures based on the electron density have been tested in an analysis of (a) the inversion symmetry for heteronuclear diatomic molecules, for the eclipsed and staggered conformations of ethane and tetrafluoroethane, and for a series of octahedral sulfur halides; (b) the reflection symmetry of three different conformers of tetrafluoroethene; and (c) the loss of C6 symmetry along the B2u distortion mode of benzene and an analysis of rotational symmetry for different six‐member ring heterocycles. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
14.
Ryota Kudo Masahiro Sonobe Yoshiaki Chino Yu Kitazawa Mutsumi Kimura 《Molecules (Basel, Switzerland)》2020,25(23)
The synthesis and characterization of two phthalocyanine (Pc) structural isomers, 1 and 2, in which four 2,6-di(hexyloxy)phenyl units were attached directly to the 1,8,15,22- or 1,4,15,18-positions of the Pc rings, are described. Both Pcs 1 and 2 exhibited low melting points, i.e., 120 and 130 °C respectively, due to the reduction in intermolecular π-π interaction among the Pc rings caused by the steric hindrance of 2,6-dihexyloxybenzene units. The thermal behaviors were investigated with temperature-controlled polarizing optical microscopy, differential scanning calorimetry, powder X-ray diffraction, and absorption spectral analyses. Pc 1, having C4h molecular symmetry, organized into a lamellar structure containing lateral assemblies of Pc rings. In contrast, the other Pc 2 revealed the formation of metastable crystalline phases, including disordered stacks of Pcs due to rapid cooling from a melted liquid. 相似文献
15.
The molecular structures of the model systems of the polaron and the bipolaron in poly-para-phenylene (PPP) were calculated
by an ab initio molecular orbital (MO) method with fairly sophisticated approximations. The calculated models are monocations,
dications, monoanions and dianions of biphenyl, para-terphenyl, para-quaterphenyl, para-quinquephenyl and para-hexaphenyl.
The calculations show that the longer the PPP oligomer is, the stronger is the tendency to take on a non-planar twisting structure.
This was accounted for by the combination of repulsions between proximate ortho-hydrogen atoms with resonance interactions
between benzene π MOs. The magnitude of the resonance interactions was assessed by using the symmetry of benzene π MOs as
well as an analytical Hückel solution of the π MO for polyene. In addition, negatively charged polarons and bipolarons were
found to have a stronger tendency to take on a planar structure than positively charged ones. This result was also explained
by comparing the benzene π HOMO with the benzene π LUMO.
Received: 30 June 1998 / Accepted: 9 September 1998 / Published online: 23 February 1999 相似文献
16.
Dr. Soroush Naseri Dr. Inès Taarit Dr. Hélène Bolvin Prof. Dr. Jean-Claude Bünzli Dr. Alexandre Fürstenberg Dr. Laure Guénée Dr. Giau Le-Hoang Dr. Mohsen Mirzakhani Dr. Homayoun Nozary Dr. Arnulf Rosspeintner Prof. Dr. Claude Piguet 《Angewandte Chemie (International ed. in English)》2023,62(50):e202314503
Previously limited to highly symmetrical homoleptic triple-helical complexes [Er( Lk )3]3+, where Lk are polyaromatic tridentate ligands, single-center molecular-based upconversion using linear optics and exploiting the excited-state absorption mechanism (ESA) greatly benefits from the design of stable and low-symmetrical [ Lk Er(hfa)3] heteroleptic adducts (hfa−=hexafluoroacetylacetonate anion). Depending on (i) the extended π-electron delocalization, (ii) the flexibility and (iii) the heavy atom effect brought by the bound ligand Lk , the near-infrared (801 nm) to visible green (542 nm) upconversion quantum yield measured for [ Lk Er(hfa)3] in solution at room temperature can be boosted by up to three orders of magnitude. 相似文献
17.
The antisymmetrized geminal power (AGP) and sequential product of geminals(SPG) functions, the basis functions with symplectic symmetry, are linearly combined to calculate the ground state of the LiH molecule. The calculation results show that the AGP or SPG function gives the same ground state results as the linear combination. 相似文献