基于TDDFT的四种含能化合物分子在紫外光下的响应

采用含时密度泛函理论(TDDFT)计算了NTO、RDX、HMX、CL-20分子的光吸收谱、紫外光激发下分子的结构以及差分电荷密度随时间的演化。TDDFT模拟结果对比实验的感度趋势表明,在紫外光照下的激发态电子数目可作为分子水平上电子稳定性的描述符,其电子稳定性层级为NTO>CL-20>HMX>RDX。硝基脱离难易程度可作为分子水平上辐照感度的描述符,其感度层级为CL-20~RDX>HMX>NTO,NTO分子表现出最低的辐照感度。这4种火炸药分子在紫外光下发生的主要反应是脱氢、开环、硝基分离、硝基脱氧形成氮气,其中强吸电的硝基向周围转移电子起到了关键作用。不同光强诱导硝基上发生不同的电荷转移,产生不同的分解产物。模拟结果表明,光场较弱时硝基脱落形成二氧化氮,主要分解产物为二氧化氮、氢自由基。强光场下部分硝基脱氧形成亚硝基,若硝基解离能足够大,硝基可完全脱氧并脱离环状结构形成氮气,反应的中间产物包括氢、氧自由基、二氧化氮、亚硝基以及氮气分子。

碳分子线激发态特性的TDDFT方法研究

采用含时密度泛函(TDDFT)方法研究了外电场对碳分子线激发态、振子强度和偶极矩的影响,结果表明外电场的大小对碳分子线激发态激发能、振子强度等都有明显影响.碳分子线的电偶极矩随Z轴方向电场的增强而急剧增大.进一步分析表明,Z轴方向电场的存在使正负电荷分别向某端聚集,从而会对碳分子线的电子传输、伏安特性等产生一定的影响.

TDDFT研究双偶氮红活性染料的UV-vis吸收光谱

文章选取了20个以J酸及其衍生物为偶合组分的双偶氮红色活性染料,采用密度泛函理论(DFT),选用B3LYP和PBE0两种杂化泛函在6-31+G(d)基组水平上计算了染料的紫外吸收光谱。通过计算光谱与实验光谱比较发现,B3LYP计算的激发能与实验值更吻合,其绝对平均误差(MAE)为0.127 e V,PBE0给出了一个略大误差,其绝对平均误差为(MAE)为0.180 e V。染料分子的主要吸收谱峰主要源于电子从HOMO,HOMO-1,HOMO-2到LUMO,LUMO+1间的π—π*跃迁。

基于TDDFT理论的Si_8团簇结构及其电子性质的数值分析研究

采用基于广义梯度近似(GGA)的含时密度泛函TDDFT方法对Si_8团簇的空间构型与对称性,能隙及电子性质进行了模拟分析,在模拟过程中采用GGA近似方法对Si_8团簇的基态能量进行截断处理。结果表明,具有C1和C2v对称性的Si_8团簇的化学稳定性相对较好,具有Cs对称性的Si_8团簇化学稳定性最差;具有D4d对称性构型和C2v对称性3a构型的Si_8团簇的平均结合能最小,团簇的稳定性最差。

含线性共轭配体的双金属钌配合物的电子吸收光谱的TDDFT理论研究

The electronic absorption spectroscopy of the model complexes[RuCl（CO）（PH3）3]2（μ-CH=CH-CH=CH）-（CH=CH）n（n=2,3） have been investigated by using time-dependent density functional theory（TDDFT）.The solvent effects of CH2Cl2 were taken into account by using the conductor-like solvent model（COSMO（CPCM））.When the hybrid basis sets method（Lanl2DZ（f） basis sets for Ru,and 6-31G（d） basis sets for other atoms） were adopted,a satisfactory assignment of the experimental absorption spectra have been achieved.The present calculation results show that the three main experimental absorption peaks are characterized as the charge transfer from metal to ligands（MLCT）,which well agree with the experimental founding by Gladysz and Bruce.

含氯不对称配体8-羟基喹啉铝配合物电子和光谱性质的TDDFT研究

以含时密度泛函理论(TDDFT)B3LYP方法通过电子结构计算研究了含氯不对称配体8-羟基喹啉铝配合物AlQ(ClQ)_2的吸收和发射光谱性质.计算表明,第一激发态与基态结构变化主要集中在单一含氯配体中,与mer-AlQ_3相比,前线占有轨道离域程度变大而未占据轨道则定域化程度提高.最大吸收主要来自配体内电荷转移跃迁,电荷从苯酚环和氯向含氮的吡啶环跃迁.电子陷入态计算表明,抽取电子能量比AlQ_3相应值略大,与实验结果一致.

含Pt配合物电子结构和非线性光学性质的TDDFT研究

利用含时密度泛函理论(TDDFT)对trans-(PEt3)2Pt(X)(p-Ph-NO2)的有机金属配合物进行结构优化, 并计算了电子光谱和二阶非线性光学(NLO)性质, 结果表明在1064 nm光场下, 2个分子的共振效应很强, 在远离共振的1907nm的下, 分子的一阶超极化率是尿素的40倍左右。

[N-ethyl-4,4'-bipyridinium][ZnX_4](X = Cl or Br) with N-ethyl-4,4'-bipyridinium Generated In Situ:Syntheses, Structures, Fluorescence and TDDFT Calculations

Two new zinc bipyridinium compounds, [N-ethyl-4,4＂-bipyridinium][ZnX4] （X = CI （1） or Br （2）） with N-ethyl-4,4＂-bipyridinium generated in situ, have been synthesized through solvothermal reactions and structurally characterized by single-crystal X-ray diffraction analyses. Both compounds are isostructural and crystallize in the P2/c space group of monoclinic system. Compound 1： a = 8.4397（5）, b = 21.988（1）, c = 8.8777（5） А, β = 106.490（1）°, V = 1579.7（2） A3, C2H15C14N2Zn, Mr = 394.43, Z = 4, Dc = 1.658 g/cm3, S = 1.068,/a（MoKa） = 2.218 mm-1, F（000） = 796, R = 0.0295 and wR = 0.0766. Compound 2： a = 8.4154（6）, b = 22.844（2）, c = 9.0308（7） A, fl = 106.026（1）°, V = 1668.6（2） A3, Cj/HjsBraN2Zn, Mr = 572.27, Z = 4, Dc = 2.278 g/cm3, S = 1.033, /l（MoKa） = 11.038 mm＂1, F（000） = 1084, R = 0.0427 and wR = 0.1175. Both of them are characteristic of an isolated structure with the zinc atoms locating at a tetrahedral environment. In both compounds, the N-ethyl-4,4＂-bipyridinium2＋ cations and ZnX42- anions interconnect together via hydrogen bonding interactions to construct a three-dimensional （3-D） supramolecular framework. Fluorescent studies reveal that both compounds exhibit a strong emission in the green region. In combination with the theoretical calculations, we can draw a conclusion that the emissions should result from ligand-to- ligand charge-transfer （LLCT） transition.

Synthesis, Structure, Fluorescence and TDDFT Calculations of [CdBr2(imidazole)]_n

A new one-dimensional （l-D） compound [CdBr2（imidazole）], （1） has been synthesized via a hydrothermal reaction and structurally characterized by single-crystal X-ray diffraction. Compound 1 crystallizes in the Pna21 space group of orthorhombic system with a = 11.299（2）, b = 15.598（3）, c = 3.9293（6） A, V = 692.5（2） A3, CaH4Br2CdN2, Mr = 340.30, Z = 4, Dc = 3.264 g/cm3, S = 1.004, /l（MoKa） = 14.588 mm＂1, F（000） = 616, R = 0.0412 and wR = 0.1286. Compound 1 is characteristic of an infinite 1-D double chain structure with the cadmium atoms locating at an octahedral environment. The double chains interconnect together via hydrogen bonding interactions to yield a 3-D supramolecular framework. Fluorescent investigation reveals that the title compound displays an emission in the purple region. Theoretical investigation reveals that the emission is mainly ascribed to ligand-to-metal charge transfer （LMCT）, accompanied with minor ligand-to-ligand charge transfer （LLCT）.

TDDFT-SOS Studies on the Polarizabilities and Second-order Hyperpolarizabilities of Zn_3O_3 II-VI Semiconductor Clusters

The geometrical structure of semiconductor clusters including Zn3O3 was optimized by the DFT B3LYP method. With the same basis sets, dipole moments, polarizabilities and secondorder hyperpolarizabilities have been calculated and compared with the results obtained by TDDFT B3LYP method combined with sum-over-state （SOS） formula. The calculation results indicate that the dipole moments of the ground state depend on the atom radius and electronegative differences between elements and are their balance point as well. The polarizabilities of the clusters accord with the rule of the corresponding energy transformation from ground to excited state. The results predict an increase of second-order hyperpolarizabilities with increasing the distances between atoms in the clusters as well as a decrease of the polarizabilities and second-order hyperpolarizabilities in the same serial of semiconductor clusters with increasing the dipole moments of the ground states. The changes of dipole moments in ground states are inconsistent with transition moments. Spatial structure, charge transfer and other factors play an important role in composing the transition moments.

Ligand-controlled First Hyperpolarizabilities of a Series of Tetrahedral Iridium Clusters Ir_4(CO)_9L: a TDDFT Study

A series of tetrahedral iridium carbonyl clusters coordinated by systematically varied series of ligands have been studied by TDDFT method focusing on their electronic and non- linear optical properties. The clusters of Ir4（CO）12 （1）, Ir4（μ-CO）3（CO）9 （2）, Ir4（μ-L）（CO）10 （L = dppm 3, dppe 4, （Ph2P）2CHMe 5, Ph2P（CH2）3PPh2 6） and Ir4（CO）10（phen） （phen = 1,10-phen- anthroline） （7） exhibit the first static hyperpolarizabilities of medium magnitude （βtot-10×10^-30 esu）. The second order nonlinear optical response of the seven clusters increase from 0 to 23 ×10^-30 esu; the high symmetric cluster Ir4（CO）12 debases its symmetry and presents the second order nonlinear optical behavior as the coordination style of some carbonyls changes to bridge style, and then the response increases regularly with the systematical variation of the ligands. The origination of the first hyperpolarizability is discussed by the expanded orbital decomposition scheme. The results suggest the d-d electron transition from the apical iridium atom to the other three Ir atoms inside the metal skeleton, and d-πelectron transitions from metals to carbonyls are responsible for the first hyperpolarizabilities. Particularly, for cluster 7, the charge transfer from d orbitals of iridium to π＊ orbirals of phenanthroline originates the first hyperpolarizabilities.

TDDFT Study on the Electronic Excitations and First Hyperpolarizabilities of Mixed-metal Carbonyl Clusters W_2Ir_2(μ-L)(CO)_8(η～5-C_5H_4Me)_2(L=dppe/dppf)

Mixed-metal carbonyl clusters of W2Ir2（CO）10（η^5-C5H4Me）2 1 and W2Ir2（μ-L）（CO）8（η^5-C5H4Me）2 （L = dppe 2, dppf 3） have been studied by TDDFT method focusing on their electronic and nonlinear optical properties. These three clusters exhibit the first static hyperpolarizabilities of medium magnitude （βtot-10×10^-30 esu）. The origin of β is discussed by the new proposed orbital-pair decomposition scheme by Barandes et al. The result suggests that the β values of the two clusters are mainly originated from d-d electron transition within the metal skeleton, and d-p （π＊） electron transition from metals to carbonyls and phenyl. The additional coordination by the electron donor group, ferrocene, makes cluster 3 own much larger β values, and the relatively longer range charge transfer from d orbitals of ferrocene to d orbirals of Ir and W is responsible for the enhanced β values.

Microscopic mechanism of plasmon-mediated photocatalytic H_(2) splitting on Ag-Au alloy chain

Alloy nanostructures supporting localized surface plasmon resonances has been widely used as efficient photocatalysts,but the microscopic mechanism of alloy compositions enhancing the catalytic efficiency is still unclear.By using time-dependent density functional theory(TDDFT),we analyze the real-time reaction processes of plasmon-mediated H_(2) splitting on linear Ag-Au alloy chains when exposed to femtosecond laser pulses.It is found that H_(2) splitting rate depends on the position and proportion of Au atoms in alloy chains,which indicates that specially designed Ag-Au alloy is more likely to induce the reaction than pure Ag chain.Especially,more electrons directly transfer from the alloy chain to the anti-bonding state of H_(2),thereby accelerating the H_(2) splitting reaction.These results establish a theoretical foundation for comprehending the microscopic mechanism of plasmon-induced chemical reaction on the alloy nanostructures.

Plasmon-induced nonlinear response on gold nanoclusters

The plasmon-induced nonlinear response has attracted great attention in micro-nano optics and optoelectronics applications,yet the underlying microscopic mechanism remains elusive.In this study,the nonlinear response of gold nanoclusters when exposed to a femtosecond laser pulse was investigated using time-dependent density functional theory.It was observed that the third-order tunneling current was augmented in plasmonic dimers,owing to a greater number of electrons in the dimer being excited from occupied to unoccupied states.These findings provide profound theoretical insights and enable the realization of accurate regulation and control of nonlinear effects induced by plasmons at the atomic level.

DFT and TDDFT investigations on the ground and excited states for polynuclear platinum(II) complexes containing the rigid phenylacetylide ligand

We have studied the ground and excited states of the three dendriticpolynuclear Pt(ll) complexes 1-[Cl(PH3)2PtC ident to C]-3,5-[HC ident to C]C6H3 (1),1,3-[CI(PH3)2PtCident to C]2-5-[HC ident to C]C6H3 (2),and 1,3,5-[CI(PH3)2-PtC ident to C]3C6H3 (3),by using theB3LYP and UB3LYP methods,respectively.TDDFT approach with the PCM model was performed to predict theemission spectra properties of 1-3 in CH2Cl2 solution.We first predicted the excited-stategeometries for the three complexes.With the change of the number of Pt(ll) atom,1-3 show thedifferent geometry structures in both the ground and excited states;furthermore,the increase of themetal density from 1 to 3 results in the red shift of the lowest-energy emissions along theseries.The luminescent properties of 1 are somewhat different from those of 2 and 3.The emissionproperties of 2 and 3 are richer than 1.Our conclusion can give a good support for designing thehigh efficient luminescent materials.

Preparation,Structure,Fluorescence,Semiconductor Properties and TDDFT Calculation of a Mononuclear Zinc Complex with Mixed Ligands

A novel zinc complex[ZnL(bipy)(H2O)]×H2O with mixed ligands of 3-hydroxy-2-methylquinoline-4-carboxylic acid(HL)and bipy(bipy=2,2'-bipyridine)was synthesized by solvothermal reaction and its crystal structure was determined by single-crystal X-ray diffraction technique.The title compound crystallizes in the orthorhombic system of Pbca space group,and exists as an isolated mononuclear complex.The intermolecular hydrogen bonds and strongπ…πstacking interactions form a three-dimensional(3-D)supramolecular network.Solid-state photoluminescence spectrum reveals that it shows an emission in the blue region of the light spectrum.Time-dependent density functional theory(TDDFT)calculations reveal that this emission can be attributed to ligand-to-ligand charge transfer(LLCT).Solid-state diffuse reflectance data show that there is a narrow optical band gap of 1.83 eV.

TDDFT和实验结合研究丹皮酚及其西佛碱的紫外光谱

采用五个密度泛函LSDA,B3LPY,B3PW91,MPW1PW91和PBE1PBE,选择不同基组计算了气相和乙醇为溶剂下的丹皮酚及其两个丹皮酚西佛碱的激发态。LSDA不能给出合理的结果,MPW1PW91和PBE1PBE的结果和实验值接近,而B3LYP能给出准确的垂直激发能。基组中加入弥散函数有利于激发能计算精度的提高。溶剂效应对激发态计算的准确度有明显影响,极化连续模型(PCM)能较好地模拟溶剂的影响,垂直激发能计算结果明显好于气相。

CO分子在线性极化飞秒激光场中的TDDFT研究

本文运用将含时密度泛函理论和分子动力学非绝热耦合的方法,研究了CO分子在不同强度、不同极化方向的激光场中的电离和动力学行为.研究发现,激光强度越强,CO分子吸收的能量越多,电离越早且电离越强,CO分子键长变长且伸缩振动越剧烈.此外,CO分子偶极矩的变化及峰值也随着激光强度的增强而增大.对激光极化方向的研究发现,激光极化方向沿着CO分子轴向时,分子的电离最强且伸缩振动最剧烈.当激光极化角增大时,CO分子的电离逐渐被抑制且电子的偶极振动对激光极化方向表现出较强的依赖性.此外研究还表明,CO分子碳原子和氧原子周围电子的弥散方式不同且与激光极化方向有关.

茜素在不同pH值的甲醇溶液中的存在形式

为了探究茜素在不同pH值的甲醇溶液中的存在形式,设计了9种结构,利用时间依赖密度泛函(TDDFT)方法模拟了茜素的紫外可见吸收光谱和荧光发射光谱,并与不同pH值下的实验光谱进行了比较;通过检验模拟光谱与实验光谱的一致性,确定了茜素在不同pH值下的存在形式。结果表明,在酸性条件下,茜素以a_G_1和a_G_4的分子形式存在;在碱性条件下,茜素以b_G_1、b_G_4和c_G的阴离子形式存在;在基态上,a_G_3不稳定,转变为a_G_4;在激发态上,a_E_3不稳定,转变为a_E_1;在激发态上,通过荧光发射光谱和TDDFT计算证实了质子在1位羟基和9位羧基之间的转移;茜素的紫外可见吸收光谱和荧光发射光谱主要来源于分子内电荷转移。