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采用UMP2/6-311+G(3df)方法得到了FnLin+1(n=1~3)体系的8个全部实频的异构体构型,并研究了这些体系的非线性光学性质.结果表明,这类超价化合物具有较大的一阶超极化率值(β0=2299.2~12322.3a.u.).超价化合物中弥散的电子云使体系具有较低的跃迁能,从而决定了FnLin+1具有较大的一阶超极化率.提示非中心对称的超价化合物将是一类潜在的非线性光学分子. 相似文献
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3,4—二硫方酸的从头算研究 总被引:2,自引:2,他引:2
在6-31G°水平上对3,4-二硫方酸(3,4-二巯基-3-环丁烯-1,2-二酮)的3种平面构象异构体进行SCF计算,结果表明,ZZ型异构体最稳定,XE型次之,从等键反应能量分析,3,4-二太酸的稳定性,与苯作探讨其芳香性,关在6-31G水平上计算了3种构象的振动频率。 相似文献
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本文合成了1,3-取代方酸衍生物:1,3-双[4-二甲胺苯基]-2,4二羟基环丁二烯氢氧双内盐(DMCS),1,3-双[4-双十六烷胺苯基]-2,4二羟基环丁二烯氢氧双内盐(DHCS).研究了DMCS和DHCS在不同溶剂中的光物理行为,估算了DMCS、DHCS的基态与激发态之间偶极矩差值。在CTAB胶束中,除DMCS单体分子外,DMCS形成了二聚体。在二氧六环-水体系中,研究了DHCS的簇集行为,并测定了DHCS的临界簇集组成(Cψ)及临界簇集浓度(CA)。 相似文献
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在RHF/6-31G水平用CPHF方法计算了两种构型的氢链的轴向极化率,计算直到89个结构单元,已基本上达到每单元极化率的极限值。根据这些较完整的资料,讨论了拟合目标函数的选取,拟合函数的确定,以及如何选定拟合数据范围以求得最佳极限值的问题,提出了求得最可信的每单元极化率极限值的原则。 相似文献
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在6-31G水平上对3,4-二硫方酸(3,4-二巯基-3-环丁烯-1,2-二酮)的3种平面构象异构体进行SCF计算.结果表明,ZZ型异构体最稳定,ZE型次之,从等键反应能量分析3,4-二硫方酸的稳定性,与苯作比较探讨其芳香性.并在6-31G水平上计算了3种构象的振动频率. 相似文献
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近年来实验发现,通过化学键调整分子间空间取向可以提高其非线性光学(NLO)响应系数。本文以对硝基苯酚分子为单体,利用化学键将两个单体连接得到一系列二聚体分子,用量子化学方法计算了它们的分子一阶超极化率(β)。研究表明,二聚体分子的β值与单体间距离和连接方式有关,在一定距离时出现极大值;而且,此类分子的β值具有显著的溶剂效应,但与单体间距离的依赖关系和气相中相同。由此可见,通过化学键改变单体间距离和连接方式可以作为提高有机分子NLO响应系数的有效途径。 相似文献
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Ab initio geometry optimization and polarizability calculations of a series of bisphenyls, which are the model compounds of chemically different polycarbonates using HF/6‐31G and 6‐31G** basis sets are presented. Calculated absolute value of the conformationally averaged optical anisotropy (〈γ2〉) of diphenyl propane, a model analog of bisphenol A polycarbonate, is higher than the corresponding experimental value in the dilute solution phase. The calculations have reproduced the relative trend in the optical anisotropy for the different bisphenyl model compounds in a manner similar to those using semiclassical approach, by incorporation of the condensed phase polarizabilities and quantum chemically calculated geometry structure into the valence optical scheme. Individual contributions to the gas phase polarizability and optical anisotropy of the model compounds for various dihedral conformers, because of the presence of different aliphatic chemical groups, are correctly predicted by the calculations here. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011 相似文献
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利用量子化学方法对第一激发态HOOO的裂解反应进行了理论研究.所有驻点(反应物、产物和过渡态)的几何结构优化和振动分析都是在CASSCF/6-31 G(d,p)理论水平下进行的.反应路径上的选择点及驻点都在CASPT2/6-31 G(d,p)//CASSCF(19,13)/6-31 G(d,p)和MRCI/6-31 G(d,p)//CASSCF(19,13)/6-31 G(d,p)理论水平下进行单点能量校正.CASSCF,CASPT2和MRCI水平的理论计算结果显示,第一激发态HOOO的裂解反应包含一个对称性变化的过程.它首先通过了一个Cs对称性的过渡态,然后逐渐变化为线性结构,最终生成产物O2(3Σg-)和OH(2Π). 相似文献
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Bojana D. Ostoji Slobodan Mii Dragana S. orevi 《International journal of quantum chemistry》2013,113(15):1890-1898
For almost all trimethylnaphthalenes (TMNs), the transition from a planar equilibrium ring conformation to a nonplanar conformation characterized by the torsional angle of 20° results in an energy increase of less than 2.5 kcal/mol. For some of them, it is less than 1.6 kcal/mol, which indicates that these molecules can change their conformation easily through intermolecular interactions. The results of the calculations reveal a linear relationship between the averaged rigidity constant and the relative energy for all planar TMNs. The changes of rings deformational energy imposed on π‐electron systems of TMNs by medium polarity are negligible (less than 0.05 kcal/mol). The aromaticity indices, based on nucleus‐independent chemical shifts, indicate aromatic character of TMNs. The α substitution increases the ring area more than the β substitution. The increase of anisotropy of dipole polarizabilities with the decrease of the area of rings for all planar TMNs, dimethylnaphthalenes and methylnaphthalenes is noticed. © 2013 Wiley Periodicals, Inc. 相似文献
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Sphere-like compound C8H17Si(OPhC12H25)3N (1) forms mesophases. In order to investigate the relationship between molecular structure and liquid crystal properties, structural studies are carried out on the model molecules of compound 1 and its substituted derivatives using ah initio calculations. The results show that the cyano or chloro substituted tribenzosilatrane compounds R1Si(OPhR2 )3N (R1 R2 = CN or Cl) have much bigger dipole moments or anisotropy of polarizability and more like sphere than the corresponding alkyl substituted compounds. Cyano or chloro substituted tribenzosilatranes would be better candidates for sphere-like meso-gens. 相似文献
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Amatatsu Y 《Journal of computational chemistry》2002,23(10):950-956
Ab initio complete active space self‐consistent field (CASSCF) and the second order multireference Møller‐Plesset calculations have been performed to examine the photochemical behavior of styrene upon the strong S0‐S2 electronic excitation in the low‐lying excited states. The optimized structure at the S2/S1 conical intersection (CIX) is characterized by a quinoid structure. The transition state (TS) in S1 is in the vicinity of the S2/S1‐CIX. At the S1‐TS, two reaction paths branch. One is the relaxation into the stable structure in S1 and then emission into S0. The other is the radiationless decay through the S1/S0‐CIX. © 2002 Wiley Periodicals, Inc. J Comput Chem 10: 950–956, 2002 相似文献
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K. R. S. Chandrakumar Tapan K. Ghanty Swapan K. Ghosh 《International journal of quantum chemistry》2005,105(2):166-173
The polarizability of lithium clusters was studied using ab initio as well as Density Functional Theory (DFT)‐based methods. The electron correlation was found not to play any major role in the evaluation of polarizability of the lithium clusters, contrary to the case of sodium and other types of clusters. The theoretical methods used in the present study are not able to reproduce the unusual features in the size evolution of the polarizability observed experimentally. An interesting feature is that the polarizability of lithium clusters calculated by various methods at 0K temperature is found to be higher than the experimental results measured at higher temperature, which is quite unusual. The significance of these issues is highlighted and the need of highly accurate DFT exchange‐correlation functionals and ab initio methods in the study of the electronic properties of lithium clusters is emphasized. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 相似文献
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ZHANG Xinzhuang ZHEN Zhen & LIU Xinhou Technical Institute of Physics Chemistry of Chinese Academy of Sciences Beijing China 《中国科学B辑(英文版)》2005,48(4)
HNCO is a convenient photolytic source of NCO and NH radicals for laboratory kinetics studies of elementary reaction[1] and plays an important role in the combustion and atmosphere chemistry. It can re- move deleterious compounds rapidly from exhausted ga… 相似文献
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Ab initio UMP2 and UQCISD(T) calculations, with 6-311G** basis sets, were performed for the titled reactions. The results show that the reactions have two product channels: NH2+ HNCO→NH3+NCO (1) and NH2+HNCO-N2H3+CO (2), where reaction (1) is a hydrogen abstraction reaction via an H-bonded complex (HBC), lowering the energy by 32.48 kJ/mol relative to reactants. The calculated QCISD(T)//MP2(full) energy barrier is 29.04 kJ/mol, which is in excellent accordance with the experimental value of 29.09 kJ/mol. In the range of reaction temperature 2300-2700 K, transition theory rate constant for reaction (1) is 1.68 × 1011- 3.29 × 1011 mL · mol-1· s-1, which is close to the experimental one of 5.0 ×1011 mL× mol-1· s-1 or less. However, reaction (2) is a stepwise reaction proceeding via two orientation modes, cis and trans, and the energy barriers for the rate-control step at our best calculations are 92.79 kJ/mol (for cis-mode) and 147.43 kJ/mol (for trans-mode), respectively, which is much higher than 相似文献