PdSi_n(n=1～15)团簇电子结构与光谱性质的理论研究

在卡里普索(CALYPSO)结构预测的基础上,采用密度泛函理论(DFT)B3LYP方法,优化得到PdSi_n(n=1~15)团簇的基态结构,对其电子性质、红外光谱和拉曼光谱进行了讨论.结果表明,PdSi_n(n=1~15)团簇的基态构型随n值的增大由平面结构向立体结构演化;当n≤4时,PdSi_n团簇的红外与拉曼活性在450~500 cm-1范围内表现较好,当n≥5时,PdSi_n团簇的红外与拉曼活性在50~500 cm~(-1)范围内表现较好.     

Au@Gen (n=2-9)团簇的几何结构和电子性质的理论研究

本文选用密度泛函B3LYP方法在Lan L2DZ基组上对Au Gen+(n=2~9)团簇的几何结构和电子性质进行了理论研究,其中包括结构优化、平均键能、HOMO-LUMO能隙和电荷转移等。结果表明,随着锗原子数的不断增加,这些掺杂团簇逐渐形成了三维立体结构,并发现Au Ge7+和Au Ge9+两个掺杂团簇是相对稳定的,而且这些掺杂团簇的电荷转移主要是由金原子到锗原子骨架上。此外,还模拟了这些掺杂团簇的红外光谱,为以后实验研究提供有价值的理论参考。     

CaSi_n(n=1～10)团簇结构、稳定性与光谱性质的理论研究

利用密度泛函理论(DFT)中的B3LYP方法,在6-311G(d)基组的水平上系统研究了CaSin(n=1~10)团簇的几何构型、稳定性与光谱(红外与拉曼)性质.研究结果表明,CaSin团簇构型是在CaSin-1构型上戴帽1个原子而形成的;当n≥4,CaSin团簇的最低能量结构均为立体构型;Ca原子的掺杂降低了体系的化学稳定性;CaSi3与CaSi5是幻数结构;在相同的观察频段内,CaSi3团簇的红外与拉曼活性在低频段均表现较好,而在高频段拉曼活性则表现较差,与之不同的是CaSi5团簇的红外与拉曼活性在整个频段内都表现的较好.     

钴硫团簇ConS^＋n—1（n=2,3）的结构和稳定性

用ａｂ ｉｎｉｔｉｏ分子轨道方法（ＲＨＦ,ＵＨＦ）和密度泛涵（ＤＦＴ）方法研究了团簇Ｃｏ２Ｓ＾＋,Ｃｏ３Ｓ＾＋２的各种可能的几何构型和电子结构,并计算了相应的较稳定构型的振动光谱,发现Ｃｏ２Ｓ＾＋和Ｃｏ３Ｓ＾＋２团簇最稳定结构均具有Ｃｓ对称性。对团簇的成键作用机理进行了理论分析。     

用密度泛函理论研究ZrnB（n=1-13）团簇的结构及性质

利用密度泛函理论,得到了ZrnB(n=1-13)团簇的基态结构,计算并讨论了团簇能量的二阶差分和离解能.结果表明,n=2,5,12时,相应团簇较稳定,特别是Zr5B团簇的稳定性最高.同时分析了ZrnB团簇的电子性质及磁性,结果显示能隙随n值的增大出现奇偶振荡趋势,特别是ZrM12B团簇的能隙只有0.015 eV,表明该团簇已具有金属性.电倚转移随n值增大,整体呈增大趋势,除了二聚体ZrB,电荷由B原子转移到Zr原子.利用Mulliken布居分析得到二聚体ZrB(5.000 μB)和团簇Zr4B(3.000 μB)的磁矩较大,ZrnB团簇中总磁矩主要来自Zr原子的4d轨道.     

正、负和中性TiP10团簇结构与电子性质的密度泛函研究

采用密度泛函理论的B3LYP方法研究了正、负和中性TiP10团簇的几何构型和电子结构. 计算结果表明, 中性TiP10团簇的基态构型为金属夹心结构, 正、负离子团簇同样具有该基态稳定结构. 通过对基态稳定结构的分子轨道分析表明, δ键对形成夹心结构起到重要作用. 理论计算得到的中性TiP10团簇的垂直和绝热电离能分别为7.84和7.68 eV, 垂直和绝热电子亲和势分别为3.18和3.35 eV.     

用密度泛函理论研究ZrnB(n=1-13)团簇的结构及性质

利用密度泛函理论, 得到了ZrnB(n=1-13)团簇的基态结构, 计算并讨论了团簇能量的二阶差分和离解能. 结果表明, n=2, 5, 12时, 相应团簇较稳定, 特别是Zr5B团簇的稳定性最高. 同时分析了ZrnB团簇的电子性质及磁性, 结果显示能隙随n值的增大出现奇偶振荡趋势, 特别是Zr12B团簇的能隙只有0.015 eV, 表明该团簇已具有金属性. 电荷转移随n值增大, 整体呈增大趋势, 除了二聚体ZrB, 电荷由B原子转移到Zr原子. 利用Mulliken布居分析得到二聚体ZrB(5.000 μB)和团簇Zr4B(3.000 μB)的磁矩较大, ZrnB团簇中总磁矩主要来自Zr原子的4d轨道.     

Au25纳米团簇合成与应用研究进展

综述了新型金属纳米材料Au25纳米团簇的合成机理和合成工艺改进,结合Au纳米团簇荧光作用机理说明其特有的荧光特性,利用Au纳米团簇荧光性质在离子检测、生物小分子检测、蛋白质检测和生物成像方面的应用,为Au纳米团簇的研究提供参考。     

芳香性团簇的结构和光谱性质的理论研究

对近年来芳香性团簇的理论研究进行了总结,主要集中在以铝原子为主的芳香性团簇、磷属元素团簇、硼原子系列团簇以及夹层型配合物和笼型分子团簇等方面,展示了该领域的一些重要研究进展和应用前景。     

Au2、Au3小团族分子的结构和势能函数

原子团簇的结构和性质研究是当今物理学和材料学中的一个热门课题,过渡金属团簇特别是Au团簇,由于其独特的物理和化学性质而被广泛地应用于催化反应、材料吸附[1-2]和光的吸收中[3]。近年来,人们用不同的理论方法研究金原子团簇。H儯kkinen等人利用GGA方法研究了中性和阴离Au2-10团簇的性质[4];Bravo-P啨rez等人采用从头计算的HF和post-HF方法研究Au2-Au6小团簇[5],这些计算结果与实验值相比,相差较大。由于金团簇电子结构的复杂性,对Au体系考虑旋—轨耦合和电子相关效应是很重要的,这种计算的不确定性对Au的影响比IB簇的其它金属团…     

胞嘧啶…NO复合物结构与性质的理论研究

用密度泛函理论在BL3YP/6-311＋G*基组水平上对胞嘧啶…NO复合物体系进行了理论计算, 发现了6个能量极小的复合物. 其结合方式是NO的N或O原子与胞嘧啶的N—H键形成氢键, 最稳定的复合物的结合能为－9.65 kJ/mol. NO的N原子与胞嘧啶的结合具有更强的优势, N结合的复合物中NO的键长缩短, 而O结合的复合物中NO键长伸长. 同时, 对复合物的振动分析发现, 在胞嘧啶中所有的与NO结合的N—H键的伸缩频率下降, 而所有氨基的面内弯曲振动频率是增加的.     

M+(C6H6复合物结构与成键性质的理论研究

应用密度泛函理论和多体微扰理论,对阳离子与苯形成的配合物M+-C6H6 (M = H+、Li+、Na+、K+、B+、Al+、Ga+、Mg+、Ca+、Mg2+、Ca2+)的平衡几何构型、稳定性和成键性质进行了研究。计算结果表明,H+-C6H6只能形成稳定的s配合物,而其它阳离子体系只能形成稳定的p 配合物。基于自然键轨道和相关前线分子轨道分析,讨论了阳离子-p 相互作用的本质。     

The Molecular and Electronic Structure of Nickelatetrazole – A Theoretical Study

Nickelatetrazoles have been proposed as intermediates in the course of the photoreaction of Ni^II complexes of [NiP₂(N₃)₂] constitution (P₂: mono‐ or diphosphane ligands). However, any metallatetrazoles as well as their organic analogue, 5 H‐carbatetrazole, could neither be prepared nor identified up to now. Based on density functional theory (DFT) calculations, predictions are given concerning the molecular and electronic structure of tetrazoles. While 5 H‐tetrazole is indeed a rather unstable species, metallatetrazole moieties in square‐planar d⁸ transition metal complexes should be experimentally accessible.     

理论研究V2O6-的结构和电子性质

The geometrical and electronic properties of the anionic and neutral V2O6 clusters were studied with the spin unrestricted hybrid density functional B3LYP method. The calculated ground states of both clusters are different from the previous theoretical results. The ground state of V2O6- is found to be a doublet with C2v symmetry, while a doublet with D2h symmetry was previously obtained by Vyboishchikov and Sauer. For neutral V2O6, the ground state is an open-shell singlet with D2h symmetry whose energy is very close to that of the triplet state. In contrast, a closed-shell singlet with D2h symmetry was obtained by Vyboishchikov and Sauer, and Calatayud et al. found a triplet ground state with Cs symmetry. Moreover,the calculated adiabatic and vertical detachment energies of the anion cluster are in much better agreement with the experimental results of photoelectron spectroscopy than previous theoretical values.     

反式和顺式HOOOH的电子光谱的理论研究

用密度泛函方法(DFT)和全活化空间自洽场方法(CASSCF)以及耦合簇理论(CCSD)优化了反式和顺式HOOOH的平衡几何构型, 用DFT计算了HOOOH顺反异构化反应的势能曲线和谐振动频率. 用含时密度泛函理论(TD-DFT)和二阶全活化空间微扰理论(CASPT2)计算了反式和顺式HOOOH垂直激发能. 计算结果表明: (1)反式异构体比顺式异构体稳定; (2)两种稳定构型的异构化反应有两种路径; (3)对于垂直跃迁能最低的单态和叁态, 反式的垂直跃迁能比顺式的低; (4)在单激发态中, CASPT2方法预测的顺式HOOOH寿命最长的激发态为21A′′, 其跃迁能是167.43 nm, 寿命为 1.44×10−5 s; 反式HOOOH寿命最长的激发态为21A, 其跃迁能是165.52 nm, 寿命为 2.07×10−5 s.     

Theoretical Studies on the Interactions of Cations with Diazine

1 INTRODUCTION Interaction between cations and π electron systems is a kind of common and important non-covalent inter- action[1～21]. It could be observed in many systems, such as gas ion-molecule complexes and biological macromolecular proteins. Especially, in biological macromolecular systems, this interaction is signi- ficant for revealing the structures and functions of proteins or disclosing the atomic essence of protein- ligand effect. Interaction between benzene and metal ions h…     

苯-噻吩低聚物电子结构及载流子传输性质的理论研究

采用密度泛函理论(DFT)的B3LYP/6-31G(d)方法对以低聚噻吩为端基、 苯并二噻吩(TPT)和并三噻吩(TTT)为共轭桥、 炔键为连接臂的20个模型化合物进行了计算研究. 在优化中性与离子态几何构型基础上, 获得了前线轨道能级、 电离能(IPs)、 电子亲和势(EAs)、 空穴/电子重组能(λ_h/λ_e)、 载流子迁移率(μ_h/μ_e)及吸收光谱等信息. 结果表明, 炔键的引入及端基低聚噻吩的增加对LUMO能级的调控作用较为显著, 而共轭桥的类型对HOMO能级影响较大; 合理选择端基、 共轭桥和连接臂等结构单元可对该类材料吸光波段及强度进行有效调节. 一维电荷传输模型结果表明, 所设计的化合物均是潜在的双极性有机半导体材料, 其中2,7-二([2,2':5',2'-三噻吩]-5-基)苯并[1,2-b:6,5-b']二噻吩(A3)和2,7-二(二噻吩并噻吩-2-基乙炔基)苯并[1,2-b:6,5-b']二噻吩(a-3)具有较高的电子迁移率, 值得进一步的实验探索研究.     

吡啶-BH3相互作用复合物的理论研究

对吡啶-BH~3复合物分别用MP2/6-31+G^*和B3LYP/6-31+G^*进行理论计算以预测该复合物的构型及解离能,得到四种构型,在MP2优化构型基础上作CCSD/6-31+G^*单点能量计算以验证MP2与B3LYP结果的可靠性,然后用B3LYP作振动频率分析,计算了各构型的垂直电离势,最后用更大基组作单点能量计算和自然键轨道(NBO)分析。结果表明,N-B直接相连的构型最稳定,其解离能为141.50kJ/mol,MP2和B3LYP对N-H接近的构型结果相关较大,另外两种构型稳定性介于二者之间,解离能分别为15.18kJ/mol,14.06kJ/mol(MP2/6-31+G^*)。     

Theoretical Study on the Structures and Properties of Hydrogen Bonding Complexes between Diazines and Water

Density functional theory B3LYP method and second-order Moller-Plesset perturbation theory MP2 method were employed to obtain the optimized geometries of the ground state and interaction energy for diazines and water complexes. The results show that the ground state complexes have strong hydrogen bonding interaction with -20.99, -16.73 and -15.31 kJ/mol after basis set superposition error and zero-point vibration energy correction for pyridazine-water, pyrimidine-water and pyrazine-water, respectively, and large red-shift for the symmetric H-O stretching vibration frequencies due to the formation of N…H-O hydrogen bond in the diazine-water complexes. The NBO analysis indicates that intermolecular charge transfer are 0.0316, 0.0255 and 0.0265 e respectively. In addition, the first singlet （n,n＊） vertical excitation energy of the monomer and the hydrogen bonding complexes between diazines and water was investigated by time-dependent density functional theory.     

Electronic Structure and Optical Properties of the Surface F-Centers in MgO: A Theoretical Analysis by DFT Approach

Electronic structure of Mg9O9 and Mg9O8 clusters modeling nano-crystalline powders of magnesium oxide has been analyzed within the frames of the density functional theory (DFT). In the framework of time-dependent DFT method (TD-DFT), the relationship between the surface and bulk properties of nano-crystals is analyzed based on variations in the density of electronic states (DOS) and changes of electronic spectra. The spectroscopy of spatial defects like low-coordinated oxygen ions and of surface point defects like F⁺- and F-centers is investigated. Optical properties of the nano-sized crystalline magnesium oxide are characterized by a spectrum of absorption bands in the range of 1-5 eV. Point defects such as F-centers absorb light in the range of 1.2-1.5 eV. Spatial defects O_LC in nano-crystals generate absorption bands in the range of 2.5-5.0 eV. According to calculations, there is no direct relation between coordination numbers of surface ions and excitation energies. Theoretical excitation energies are compared with experimental optical properties of the F⁺- and F-centers.