A Theoretical Study of Nonlinear Second-Order Optical Properties of Substituted Silanes

ＡＴｈｅｏｒｅｔｉｃａｌＳｔｕｄｙｏｆＮｏｎｌｉｎｅａｒＳｅｃｏｎｄ┐ＯｒｄｅｒＯｐｔｉｃａｌＰｒｏｐｅｒｔｉｅｓｏｆＳｕｂｓｔｉｔｕｔｅｄＳｉｌａｎｅｓ＊ＳｕｐｐｏｒｔｅｄｂｙｔｈｅＮａｔｉｏｎａｌＮａｔｕｒａｌＳｃｉｅｎｃｅＦｏｕｎｄａｔｉｏｎｏ...     

Introduction to the Chinese Society of Chemical Science and Technology in the UK(CSCST-UK)and Chinese Section of Society of Chemical Industry(SCI-CS)

ＴｈｅＣｈｉｎｅｓｅＳｏｃｉｅｔｙｏｆＣｈｅｍｉｃａｌＳｃｉｅｎｃｅａｎｄＴｅｃｈｎｏｌｏｇｙｉｎｔｈｅＵＫ(ＣＳＣＳＴ ＵＫ)ｉｓｐｒｏｆｅｓｓｉｏｎａｌｏｒｇａｎｉｚａ ｔｉｏｎｏｒｇａｎｉｚｅｄｂｙＣｈｉｎｅｓｅＳｃｈｏｌａｒｓｃｕｒｒｅｎｔｌｙｗｏｒｋｉｎｇｉｎｔｈｅＵＫ .ＩｔｗａｓｅｓｔａｂｌｉｓｈｅｄｉｎＡｐｒｉｌ 1994ｉｎＬｏｎｄｏｎｗｉｔｈｔｈｅｈｅｌｐｏｆｔｈｅＥｄｕｃａｔｉｏｎＳｅｃｔｉｏｎｏｆＣｈｉｎｅｓｅＥｍｂａｓｓｙｉｎｔｈｅＵＫａｆｔｅｒｔｈｅｉｎｉｔｉａｔｉｏｎｆｒｏｍ…     

The Division of Analytical Chemistry of The Federation of European Chemical Societies

ＦＥＣＳ ,ｔｈｅＦｅｄｅｒａｔｉｏｎｏｆＥｕｒｏｐｅａｎＣｈｅｍｉｃａｌＳｏｃｉ ｅｔｉｅｓ,ｃｏｍｐｒｉｓｅｓａｎｕｍｂｅｒｏｆＤｉｖｉｓｉｏｎｓａｎｄＷｏｒｋｉｎｇＰａｒ ｔｉｅｓｓｐｅｃｉａｌｉｚｉｎｇｉｎｃｅｒｔａｉｎｆｉｅｌｄｓｓｕｃｈａｓＦｏｏｄＣｈｅｍ ｉｓｔｒｙ ,ＥｌｅｃｔｒｏｃｈｅｍｉｓｔｒｙｏｒＣｈｅｍｉｃａｌＥｄｕｃａｔｉｏｎ .ＡｍｏｎｇｔｈｅｍｔｈｅＤｉｖｉｓｉｏｎｏｆＡｎａｌｙｔｉｃａｌＣｈｅｍｉｓｔｒｙ ,ＤＡＣ ,ｉｓｏｎｅｏｆｔｈｅｌａｒｇｅｓｔｗｉｔｈｒｅｓｐｅｃｔｔｏ…     

Microcalorimetric Character of Inhibition of Salicylaldehyde Glucosamine Schiff Base SG on Bacterial Metabolism

ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅＳｃｈｉｆｂａｓｅａｎｄｉｔｓｍｅｔａｌｃｏｍｐｌｅｘｅｓａｒｅｏｆａｎｔｉｂａｃｔｅｒｉａｌａｎｄａｎｔｉｃａｎｃｅｒｂｉｏａｃｔｉｖｉｔｉｅｓ，ｔｈｅｙｈａｖｅｂｅｅｎａｒｅｓｅａｒｃｈｓｕｂｊｅｃｔｏｆｍｕｃｈ...     

Synthesis of the Precursor of Tetrasaccharide from Laminin

ＳｙｎｔｈｅｓｉｓｏｆｔｈｅＰｒｅｃｕｒｓｏｒｏｆＴｅｔｒａｓａｃｃｈａｒｉｄｅｆｒｏｍＬａｍｉｎｉｎＸｉａｏＸｉａｎｇＺＨＵ；ＰｉｎｇＹｕＤＩＮＧ；ＭｅｎｇＳｈｅｎＣＡＩ（ＤｅｐａｒｔｍｅｎｔｏｆＯｒｇａｎｉｃＣｈｅｍｉｓｔｒｙ，ＳｃｈｏｏｌｏｆＰ...     

Theoretical Studies on the Structures and Reactions of Halocarbenoids(Ⅰ) Structures and Stability of

ＴｈｅｏｒｅｔｉｃａｌＳｔｕｄｉｅｓｏｎｔｈｅＳｔｒｕｃｔｕｒｅｓａｎｄＲｅａｃｔｉｏｎｓｏｆＨａｌｏｃａｒｂｅｎｏｉｄｓ（Ⅰ）ＳｔｒｕｃｔｕｒｅｓａｎｄＳｔａｂｉｌｉｔｙｏｆＣｈｌｏｒｏｃａｒｂｅｎｏｉｄＣＨＣｌ_２ＬｉＬＩＪｉ－ｈａｉ，ＦＥＮＧＳ?..     

A Short and Highly Stereoselective Synthesis of Cerebrosterol

Ｃｅｒｅｂｒｏｓｔｅｒｏｌ (2 4Ｓ ｈｙｄｒｏｘｙｃｈｏｌｅｓｔｅｒｏｌ,1)ｆｏｒｍｅｄｉｎｓｍａｌｌａｍｏｕｎｔｓｉｎｈｕｍａｎａｎｄａｎｉｍａｌｂｒａｉｎ1ｆｒｏｍｃｈｏｌｅｓ ｔｅｒｏｌｉｓｉｍｐｏｒｔａｎｔｆｏｒｃｈｏｌｅｓｔｅｒｏｌｈｏｍｅｏｓｔａｓｉｓｉｎｔｈｉｓｏｒｇａｎ .Ｔｈｅｅｘｃｅｓｓｃｈｏｌｅｓｔｅｒｏｌｉｓｃｏｎｖｅｒｔｅｄｉｎｔｏ 2 4Ｓ ｈｙｄｒｏｘｙ ｃｈｏｌｅｓｔｅｒｏｌｂｙａｕｎｉｑｕｅｂｒａｉｎ ｓｐｅｃｉｆｉｃ 2 4Ｓ ｈｙｄｒｏｘｙｌａｓｅ ,ｗｈｉｃｈｃｏｕｌｄｂｅｒ…     

Capillary Electrophoretic Separation of Monosialogangliosides by using cyclodectrin and borax as selectors

ＴＯｗｈｏｍｃｏ￣ｎｄｅｎＣｅｓｈｏｕｌｄｂｅａｄｄｒｅＳＳｅｄＢｏｔｈＭＳＧＬＳａｎｄＣＤｃｏｎｔａｉｎｈｙｄｒｏｎｙｌｇｒｏｕｐｓｏｎａｄｊａｃｅｎｔｃａｎｏｎａｔｏｍｓ．ＩｔｈａｓｂｅｅｎｋｎｏｗｎｔｈａｔｐｏｌｙｈｙｄｒｏｘｙｃｏｍｐｏｕｎｄｓｃａｎｆｏｒｍｉｒｏｎｉｃｃｏｍｐｌｅｘｅｓｗｉｔｈｂｏｒａｘＩＳ］．Ｂ｝＇ａｄｄｉｎｇｂｏｒａｘｔｏｔｈｅｂｕｆｆｅｒｃｏｎｔａｉｎｉｎｇｏｒ－ＣＤ，ｔｈｅｓｅｐｂｏｏｎｏｆＭＳＧＬＳｔｉ．ａｓｉｍｐｒｏｖｅｄｄｒ￣ｃａｌｌｙ．ａｓｓｈｏｗｎｉｎＦｉｇ．１．ＩｍｐｒｏｖｅｍｅｎｔｏｆｓｅｌｅｃｔｉｖｉｔｙｗａｓｐｒｅｓＵｍａｂｌ｝．ｄｕｅｔｏｃｏｍｐｌｅｘａｔｉｏｎｏｆｔｈｅＭＳＧＬＳｗｉｔｈｂｏｒａｘａｎｄａ－ＣＤｉｎｔｈｅｓｏｌｕｔｉｏｎ．ＯｕｒｏｂｓｅｒｖａｔｉｏｎｓｓｈｏｗｅｄｔｈａｔｔｈｅｃｏｎｃｅｎｔｒａｔｉｏｎｏｆｂｏｒａｘａｎｄｔｈｅＰＨｉｎｔｈｅｂａｅｒａｒｅｃｒｉｔｉｃａｌｆａｃｔｏｒｓｔｈｅｃｈｎｇｔｈｅｒｅｓｏｌｕｈｏｎｏｆＭＳＧＬＳ．ＤｅｃｒｅａｓｉｎｇｔｈｅｃｏｎｃｅｎｔｒａｔｉｏｎＯｆｂｏｒａｘｆｒｏｍ１００ｔｏ５０ａｍｏｋｓ．     

Structure and Stability of Interstellar Molecule C_3S

ＩｎｔｒｏｄｕｃｔｉｏｎＳｍａｌｌｃｌｕｓｔｅｒｓｃｏｎｔａｉｎｉｎｇｃａｒｂｏｎａｎｄｓｕｌｆｕｒ,ｓｕｃｈａｓＣＳ ,Ｃ2 ＳａｎｄＣ3 Ｓ ,ｗｈｉｃｈｐｏｓｓｅｓｓｌａｒｇｅｐｅｒｍａｎｅｎｔｄｉｐｏｌｅｍｏｍｅｎｔｓａｎｄｈａｖｅｂｅｅｎｉｄｅｎｔｉｆｉｅｄｉｎｔｈｅｃａｒｂｏｎｓｔａｒＩＲＣ+ 10°2 16ａｎｄｉｎｔｈｅＴａｕｒｕｓｃｏｌｄｍｏｌｅｃｕｌａｒｄｅｎｓｅｃｌｏｕｄＴＭＣ 1,1 7ｈａｖｅａｔｔｒａｃｔｅｄｍｕｃｈａｔｔｅｎｔｉｏｎｂｅｃａｕｓｅｏｆｔｈｅｉｒｉｍｐｏｒｔａｎｔｒｏｌｅｓ…     

Effect of Substituting Group on the Calculated Nonlinear Second－Order Optical Susceptibilities of Substituted Thiophene Derivatives with Quinoidlike Conformation

ＥｆｆｅｃｔｏｆＳｕｂｓｔｉｔｕｔｉｎｇＧｒｏｕｐｏｎｔｈｅＣａｌｃｕｌａｔｅｄＮｏｎｌｉｎｅａｒＳｅｃｏｎｄ－ＯｒｄｅｒＯｐｔｉｃａｌＳｕｓｃｅｐｔｉｂｉｌｉｔｉｅｓｏｆＳｕｂｓｔｉｔｕｔｅｄＴｈｉｏｐｈｅｎｅＤｅｒｉｖａｔｉｖｅｓｗｉｔｈＱｕｉｎ...     

用密度泛函和遗传算法研究Cun (n≤20) 团簇的尺寸效应

结合遗传算法和Gupta多体势系统地搜索金属团簇Cu_n (n≤20)的几何结构, 并利用密度泛函方法进一步确定最稳定构型. 分析了平均键长、平均配位数、结合能、二阶差分能、电离势和电子亲和势等性质随着尺寸的变化规律. 发现在Cu₇处团簇最稳定构型从二维结构转向三维结构, Cu_n (n≤20)团簇的幻数为8, 13, 20. 团簇的键长、配位数和结合能属性随着尺寸的增长而递增最终接近相应的体相值; 而二阶差分能、电离势和电子亲和势随着尺寸增加出现奇偶交替, 说明偶数电子形成闭壳层结构, 比相邻团簇更稳定.     

CnBδ(δ=0, ±1; n =1～6)团簇的结构、稳定性和光谱

采用密度泛函理论(DFT)的B3LYP方法,在6-31G*和6-311＋G(3df)水平上对C_nB(n=1～6)团簇及其阴离子和阳离子的几何构型和电子结构进行了优化和振动频率计算.得到了C_nB(n=1～6)团簇的电离能,绝热电子亲合势以及C_nB^δ(δ=0,±1)团簇的能隙.结果表明C_nB^－(n=1～6)团簇的基态构型均为线形,这与等电子的C_n簇合物的结构是一致的; C_nB(n=1～6)团簇的基态构型中,除C₂B为不对称的三角形,C₆B为具有C_2v对称性的环状结构外,其余均为线形结构.阳离子团簇中n=2、3、6的基态结构具有C_2v对称性外,其它几个均为线形结构.从几何参数和振动频率上发现,采用密度泛函B3LYP方法在6-311＋G(3df)和6-31G*两种基组上计算得到的键长参数和振动频率非常接近,说明B3LYP方法在计算C_nB簇合物结构参数上对于基组的选择是不太敏感的.通过对C_nB(n=1～6)的光电子能谱性质的研究发现,C₄B容易获得一个电子形成阴离子团簇,但失去一个电子是很困难的,这与实验上观测到的结果非常吻合.     

Theoretical investigation on the adsorption of lithium atom on the Sin cluster (n=2–7)

Ab initio calculations are carried out to study the adsorption of Lithium atom on the Si_n cluster with n ranging from 2 to 7. At the MP2/6-31G(d) level, the structures of the neutral Si_n clusters and the Si_nLi clusters (n=2–7) are optimized. The single-point energy at QCISD/6-311+G(d,p) level for the optimized isomers are further performed. Harmonic vibrational frequency analysis at the MP2/6-31G(d) level is also undertaken to confirm that the optimize geometries are stable. Based on our results, the most favorable sites for Li adsorption on the Si_2–7 clusters are the bridge sites. In addition, the vertical ionization energies of the Si_nLi clusters and the electron affinities of the Si_n clusters are also calculated. The clear parallelism between the vertical ionization energies of Si_nLi and the electron affinities of Si_n is found. This is consistent with the fact that the framework of the Si_n in the Si_nLi cluster is similar to the structure of the corresponding negative ion .     

Theoretical study of Al(n) and Al(n)O (n = 2-10) clusters

The stable structures, energies, and electronic properties of neutral, cationic, and anionic clusters of Al(n) (n = 2-10) are studied systematically at the B3LYP/6-311G(2d) level. We find that our optimized structures of Al5(+), Al9(+), Al9(-), Al10, Al10(+), and Al10(-) clusters are more stable than the corresponding ones proposed in previous literature reports. For the studied neutral aluminum clusters, our results show that the stability has an odd/even alternation phenomenon. We also find that the Al3, Al7, Al7(+), and Al7(-) structures are more stable than their neighbors according to their binding energies. For Al7(+) with a special stability, the nucleus-independent chemical shifts and resonance energies are calculated to evaluate its aromaticity. In addition, we present results on hardness, ionization potential, and electron detachment energy. On the basis of the stable structures of the neutral Al(n) (n = 2-10) clusters, the Al(n)O (n = 2-10) clusters are further investigated at the B3LYP/6-311G(2d), and the lowest-energy structures are searched. The structures show that oxygen tends to either be absorbed at the surface of the aluminum clusters or be inserted between Al atoms to form an Al(n-1)OAl motif, of which the Al(n-1) part retains the stable structure of pure aluminum clusters.     

Density functional calculation of the structure and electronic properties of Cu(n)O(n) (n = 1-8) clusters

Ab initio simulations and calculations were used to study the structures and stabilities of copper oxide clusters, Cu(n)O(n) (n = 1-8). The lowest energy structures of neutral and charged copper oxide clusters were determined using primarily the B3LYP/LANL2DZ model chemistry. For n ≥ 4, the clusters are nonplanar. Selected electronic properties including atomization energies, ionization energies, electron affinities, and Bader charges were calculated and examined as a function of n.     

Probing the electronic structure of early transition-metal oxide clusters: polyhedral cages of (V2O5)n(-) (n = 2-4) and (M2O5(2)(-) (M = Nb, Ta)

Vanadium oxide clusters, (V2O5)n, have been predicted to possess interesting polyhedral cage structures, which may serve as ideal molecular models for oxide surfaces and catalysts. Here we examine the electronic properties of these oxide clusters via anion photoelectron spectroscopy for (V2O5)n(-) (n = 2-4), as well as for the 4d/5d species, Nb4O10(-) and Ta4O10(-). Well-resolved photoelectron spectra have been obtained at 193 and 157 nm and used to compare with density functional calculations. Very high electron affinities and large HOMO-LUMO gaps are observed for all the (V2O5)n clusters. The HOMO-LUMO gaps of (V2O5)n, all exceeding that of the band gap of the bulk oxide, are found to increase with cluster size from n = 2-4. For the M4O10 clusters, we find that the Nb/Ta species yield similar spectra, both possessing lower electron affinities and larger HOMO-LUMO gaps relative to V4O10. The structures of the anionic and neutral clusters are optimized; the calculated electron binding energies and excitation spectra for the global minimum cage structures are in good agreement with the experiment. Evidence is also observed for the predicted trend of electron delocalization versus localization in the (V2O5)n(-) clusters. Further insights are provided pertaining to the potential chemical reactivities of the oxide clusters and properties of the bulk oxides.     

A Gaussian-3 theoretical study of small silicon-lithium clusters: electronic structures and electron affinities of SinLi(-) (n = 2-8)

The molecular structures of neutral Si n Li ( n = 2-8) species and their anions have been studied by means of the higher level of the Gaussian-3 (G3) techniques. The lowest energy structures of these clusters have been reported. The ground-state structures of neutral clusters are "attaching structures", in which the Li atom is bound to Si n clusters. The ground-state geometries of anions, however, are "substitutional structures", which is derived from Si n+1 by replacing a Si atom with a Li (-). The electron affinities of Si n Li and Si n have been presented. The theoretical electron affinities of Si n are in good agreement with the experiment data. The reliable electron affinities of Si n Li are predicted to be 1.87 eV for Si 2Li, 2.06 eV for Si 3Li, 2.01 eV for Si 4Li, 2.61 eV for Si 5Li, 2.36 eV for Si 6Li, 2.21 eV for Si 7Li, and 3.18 eV for Si 8Li. The dissociation energies of Li atom from the lowest energy structures of Si n Li and Si atom from Si n clusters have also been estimated respectively to examine relative stabilities.     

Structural and electronic properties of Si(n), Si(n)-, and PSi(n-1) clusters (2 < or = n < or = 13): Theoretical investigation based on ab initio molecular orbital theory

The geometric and electronic structures of Si(n), Si(n)-, and PSi(n-1) clusters (2 < or = n < or = 13) have been investigated using the ab initio molecular orbital theory formalism. The hybrid exchange-correlation energy functional (B3LYP) and a standard split-valence basis set with polarization functions (6-31+G(d)) were employed to optimize geometrical configurations. The total energies of the lowest energy isomers thus obtained were recalculated at the MP2/aug-cc-pVTZ level of theory. Unlike positively charged clusters, which showed similar structural behavior as that of neutral clusters [Nigam et al., J. Chem. Phys. 121, 7756 (2004)], significant geometrical changes were observed between Si(n) and Si(n)- clusters for n = 6, 8, 11, and 13. However, the geometries of P substituted silicon clusters show similar growth as that of negatively charged Si(n) clusters with small local distortions. The relative stability as a function of cluster size has been verified based on their binding energies, second difference in energy (Delta2 E), and fragmentation behavior. In general, the average binding energy of Si(n)- clusters is found to be higher than that of Si(n) clusters. For isoelectronic PSi(n-1) clusters, it is found that although for small clusters (n < 4) substitution of P atom improves the binding energy of Si(n) clusters, for larger clusters (n > or = 4) the effect is opposite. The fragmentation behavior of these clusters reveals that while small clusters prefer to evaporate monomer, the larger ones dissociate into two stable clusters of smaller size. The adiabatic electron affinities of Si(n) clusters and vertical detachment energies of Si(n)- clusters were calculated and compared with available experimental results. Finally, a good agreement between experimental and our theoretical results suggests good prediction of the lowest energy isomeric structures for all clusters calculated in the present study.     

Theoretical study of the structural and electronic properties of SimGen and SimGen- (s = m + n <or= 7) clusters

Ground-state structures, vibrational frequencies, HOMO-LUMO energy gap, electron affinities, and cluster mixing energy of binary semiconductor clusters SimGen in the range s = m + n 相似文献   

羰基硼化合物(BCO)n(n==1～12)的理论研究

运用HF/3-21G方法和密度泛函理论(DFT)的B3LYP/6-31G*方法, 对羰基硼化合物(BCO)n(n=1~12)的各种可能结构进行了优化, 对在B3LYP/6-31G*水平上得到的几何构型、电子态、结合能、振动频率、核独立化学位移(NICS)、能量二次差分和热力学性质进行了理论研究, 得到了(BCO)n(n=1~12)结构的稳定性信息. 十二种基态结构都是端配位(μ1-CO), (BCO)n(n=1~3, 5, 6) 的基态是线型或平面结构, (BCO)n(n=4, 7~12)的基态是笼状结构; B—C平均键能呈现奇偶交替现象, 偶数的结构比奇数稳定; 能量二次差分得到同样的结论；羰基的振动频率与实验值非常吻合; 热力学性质的研究对实验具有重要的指导意义.