团簇LaO的理论研究

采用密度泛函理论研究LaO团簇体系。中性分子LaO的基态是两重态(2Σ),阴离子LaO-和阳离子LaO 的基态都是单重态(1Σ)。使用不同的方法计算团簇LaO的电子亲和能和电离能。计算结果表明用BLYP方法和弥散极化基组计算结果和实验数据吻合较好。用含时密度泛函理论计算团簇LaO的低能激发态,从理论上归属LaO-的光电子能谱的谱峰和LaO的吸收光谱的谱峰。计算得到与实验一致的结果。     

CH,NH和OH自由基基态与低激发态分子结构与势能函数

用电子相关耦合簇方法CCSD(T)和aug-cc-pVTZ基函数计算研究了CH, NH和OH自由基分子基态与低激发态的结构与势能函数，导出了分子的光谱数据.结果表明，CH, NH和OH自由基分子基态分别为X²Π，X³Σ和X²Π，基态与低激发态的势能函数均可用Murrell-Sorbie function来表达.CH自由基分子低激发态a⁴Σ^－和⁶Σ^－的绝热 关键词： 电子相关耦合方法 势能函数 结构 自由基     

Au_nAg_m~-(n+m=2～4)负离子团簇光脱附电子谱计算

利用密度泛函理论,通过几何优化和态密度计算了Au_nAg_m^-（n+m=2～4）团簇的光电子光谱,结果显示只有Au₂Ag₂^-团簇的第一个峰发生了0.5eV的红移,而其它团簇的峰位置符合的很好,因此理论计算给出的团簇结构是合理的.     

Cu13±团簇几何和电子结构的密度泛函研究

借助遗传算法结合Gupta原子间相互作用势.本文采用密度泛函理论系统研究了带电Cu₁₃^±团簇的基态与低激发态的几何结构和电子结构,并与中性Cu₁₃团簇的结果进行了对比.计算结果表明:对Cu₁₃ⁿ（n=0,±1）团簇,高对称性几何构型在众多异构中无能量竞争性优势,团簇基态结构皆为非紧致低对称性结构,对Cu₁₃找到一种新的低对称性最低能结构;带电明显影响团簇结构稳定性,带电Cu₁₃^±团簇与中性Cu₁₃团簇的结构稳定性序列显著不同;基态Cu₁₃ⁿ（n=0,±1）团簇具有磁矩最小化效应,而其高对称性结构则有较大磁矩;计算所得Cu₁₃团簇电离能及电子亲和势与实验结果相符.     

六参数高精度双原子分子解析势能函数

提出一种构造解析势能函数的新方法,得到一种六参数解析势能函数,该势能函数适用于多种基本类型的双原子分子.用同核中性基态双原子分子Li₂-X¹Σ_g⁺、Na₂-X¹Σ_g⁺,异核带电基态双原子分子离子(BC)^--X³∏,异核中性激发态双原子分子PbS-A¹Σ⁺、BaO-A¹Σ,异核带电激发态双原子分子离子(CS)⁺-A²∏,同核中性激发态双原子分子K₂-B¹∏_u,同核带电激发态双原子分子离子N₂⁺-B²Σ_u⁺等共36个算例对该势能函数进行验证,计算结果与RKR(Rydberg-Klein-Rees)数据或振动能谱实验数据高精度符合.同时发现,在分子振动能谱计算精度方面,该势能函数总体上优于Murrell-Sorbie势能函数.     

金属有机化学气相淀积技术制备GaMnN薄膜材料光学性质研究

研究由MOCVD 技术制备的 GaMnN 外延薄膜光吸收谱.实验发现Mn掺杂后较未掺杂GaN吸收系数在近紫外区增加,在吸收谱低能区144 eV附近观察到吸收峰,吸收系数随Mn浓度的增加而增大.实验结果与基于密度泛函理论的第一性原理计算结果一致,结合理论计算分析认为144 eV附近的吸收峰源于Mn³⁺离子e态与t₂态间的带内跃迁⁵T₂→⁵E. 关键词： GaMnN MOCVD 密度泛函理论 光学性质     

AuZn和AuAl分子基态与低激发态的势能函数与热力学性质

用密度泛函理论B3LYP方法计算研究AuZn和AuAl分子基态与低激发态的结构与势能函数,导出分子的光谱数据.结果表明,AuZn和AuAl分子基态分别为X²Σ和X¹Σ,基态与低激发态的势能函数均可用Murrell-Sorbie函数来表达.AuZn分子低激发态a⁴Σ的绝热激发能为43529kJ/mol,AuAl分子低激发态a³Σ的绝热激发能为19991kJ/mol.计算固体AuZn和AuAl的内能和熵时,近似以气体分子的电子能和振动能代替固体分子的内能,用电子熵和振动熵代替固体分子的熵.在此近似下,计算得到AuZn和AuAl基态与低激发态固态分子生成反应热力学性质与温度的关系. 关键词： AuZn和AuAl B3LYP 热力学性质 势能函数     

AunY(n＝1—9)掺杂团簇的结构和电子性质研究

采用相对论有效原子实势(RECP)近似和密度泛函(B3LYP)方法，选择LANL2DZ基组，优化得到了Au_nY(n＝1—9)二元掺杂团簇稳定的基态结构和电子性质.研究结果表明，掺杂Y原子的Au_nY(n＝1—9)团簇随n的变化，其电离势、电子亲合能和费米能级与Au_n(n＝2—9)一样具有“奇-偶”振荡效应；团簇离子的稳定性具有“幻数”现象，Au₂Y⁺和Au₆Y⁺比其他团簇离子更稳定，与质谱实验结果一致；同一团簇中，团簇最稳定的异构体(基态)是趋于Y原子有最大的邻近的Au原子数. 关键词： Au-Y团簇 密度泛函 平衡几何结构 电子性质     

特丁基对苯二酚的光谱及密度泛函研究

特丁基对苯二酚是重要的食品抗氧化剂.理论上,基于密度泛函理论,采用B3LYP泛函及6-311G(d,p)基组在气相环境下优化分子的结构并进行频率计算.在此基础上,基于含时密度泛函理论,选用SMD(solvation model based on density)溶剂模型,利用B3LYP泛函并结合def2-TZVP基组计算分子在无水乙醇溶剂中的前50个激发态.再通过Multiwfn软件对红外光谱做振动分析并考察分子间相互作用对红外光谱的影响,对紫外光谱做分子轨道和电子空穴分析.实验上,通过KBr压片法,利用傅里叶红外变换光谱仪测定样品红外光谱.采用液相法,以乙醇为溶剂,利用紫外可见分光光度计测定样品紫外光谱.通过对比分析可知,理论光谱与实验光谱总体吻合较好.红外光谱各基团的特征吸收峰都较为明显且较好吻合,特丁基对苯二酚二聚体存在氢键作用,这使得O—H键的强度被削弱,导致吸收频率降低并在3670—3070 cm^-1处出现一个宽峰.紫外光谱主要由基态跃迁至第1,2,6,7激发态形成,最大吸收峰位于200 nm以下,为π→π^*和s→π^*跃迁形成,268.8 nm和221.4 nm处的吸收峰均为n→π^*和π→π^*跃迁形成.由电子空穴图可知,这4个主要激发均为电子局域激发.     

Na5, Na6和Na7团簇光学吸收谱的理论研究

以含时密度泛函理论为基础，结合从头赝势方法运用含时局域密度近似计算了Na₅，Na₆和Na₇团簇的动力学极化强度，并通过傅里叶变换得出了团簇的光学吸收谱.研究表明，计算结果可以较好地再现实验谱，而且Na₆和Na₇团簇的结果和组态相互作用的结果符合较好.二维结构和三维结构的Na₆团簇的计算结果表明，只有二维结构可出现低于2 eV以下的峰，而且二维结构光谱的计算结果与实验结果符合较好. 关键词： 光吸收谱 Na团簇 含时局域密度近似     

Analysis of Dissociation—Recombination Processes for the CO<Subscript>2</Subscript> Molecule with the Spin—Orbit Coupling Taken into Account

The dissociation CO₂(X¹Σ) + M → CO(X¹Σ) + O(³P) + M and recombination CO(X¹Σ) + O(³P) + M → CO₂(X¹Σ) + M processes are considered with the spin—orbit coupling taken into account in the ground and several excited states of the CO₂ molecule. Because of the specific features of mutual position of potential energy surfaces of the CO₂ molecule in the ground and several excited states and the large values of spin—orbit interaction matrix elements, which causes the quantum nonadiabatic transition of the molecule from one state to another, these processes become effectively spin-allowed and the rate constants for the nonadiabatic reactions have large values. The proposed dissociation and recombination mechanisms include reactions involving singlet—triplet crossings.     

The electronic spectrum of PN. A configuration interaction study

Potential energy curves were calculated for the ground state of PN and for all excited singlet and triplet states resulting from the 2π → 3π, 7σ → 3π, 2π → 8σ, and 7σ → 8σ orbital excitations. CI studies at 4 Å served to establish dissociation energies. Spectroscopic constants were calculated, and are in good agreement with those of the known X¹Σ⁺ and A¹Π states. Overall, their similarity with those observed for N₂ is striking. Various states considered to perturb the known excitations are discussed. The recently discovered second ¹Σ⁺ state is included.     

Excitation transfer between excited electronic states of the H2 molecule due to interaction with a CO2 Laser beam

A spectroscopic study of the band systemsG ¹ Σ _g →B ¹ Σ _u andI ¹ Π _g →B ¹ Σ _u of H₂ emitted by a glow discharge in H₂ gas showed that the populations of theG ¹ Σ _g (v, J) states decrease for the benefit of theI ¹ Π _u (v′, J′) states when the discharge is irradiated by a powerful CO₂ Laser beam (power density 70 kW/cm²). The effect is interpreted as an absorption process in which two Laser photons intervene according to the transition scheme:G ¹ Σ _g →B″¹ Σ _u →I ¹ Π _g. A change of the populations of excited electronic states should lead to a change of the populations of excited atomic states as well.     

Low-lying electronic states of LiF molecule with inner electrons correlation

The potential energy curves and dipole moments of the low-lying electronic states of LiF molecule are performed by using highly accurate multi-reference configuration interaction with Awcv5z basis sets. 1s, the inner shell of Li is considered as the closed orbit, which is used to characterise the spectroscopic properties of a manifold of singlet and triplet states. 16 electronic states correlate with two lowest dissociation channels Li(²S)+F(²P) and Li(²P)+F(²P) are investigated. Spectroscopic parameters of the ground state X¹Σ⁺ have been evaluated and critically compared with the available experimental values and the other theoretical data. However, spectroscopic parameters of 1³Π, 1¹Δ, 1¹Σ^?, 1¹Π, 1³Σ⁺, 2³Σ⁺, 1³Δ, 1³Σ^?, 2³Π, 2¹Π, 3³Π, 3¹Π and 3³Σ⁺ states are studied for the first time. These 13 excited states have shallow potential wells, and the dispersion coefficients of these excited states are predicted. In additional, oscillator strengths of excited states at equilibrium distances are also predicted.     

The B2Σ+ → A2Πi system of silicon nitride,SiN

The 440-nm violet-degraded ${}^2\text{Σ →}{}^2\text{Π}$ bands of SiN, which were previously assigned to a $\text{“K” → A}$ system, have been reanalyzed. These bands are shown to be Δv = 0, ±1 sequence bands of the B²Σ⁺ → A²Π system of SiN. The first reliable value of T_e(A²Π) = 994.4(1) cm^?1 has been obtained, and this determines the location of the D²Π and L²Π states with respect to the ground state. The B²Σ⁺, v = 7 and D²Π, v = 3 levels are shown to be mutually perturbing. A detailed study has been made of the perturbed X²Σ⁺, v = 8 level. The 6–8 band of the B → X system has been photographed at high resolution. A deperturbation of this band confirms T_e(A²Π), and provides the first experimental verification of the inverted nature of the A state.     

Electronic states and transitions of the TeX (X = C1, Br,I) radicals

Ab initio multireference configuration interaction calculations including spin-orbit coupling have been carried out for the first time for valence electronic states of the TeX (X = Cl, Br, I) radicals and compared with the results for the isovalent TeF and IO systems obtained earlier at a similar level of theoretical treatment. The calculated spectroscopic constants are in good agreement with experimental data in the rare cases when the latter are available. It is shown that the X² II(σ²π⁴π?³) ground state bonding becomes consistently weaker down the TeX group (calc. D_e, = 25480cm^?1 for TeF, 12 100cm^?1 for Tel) due to the more covalent character of bonding in the heavier radicals. The first excited state, A ⁴Σ^? (π?→ σ?), is calculated to be bound in all systems. It is split into Ω 1/2 and 3/2 components, with regular ordering in the Franck-Condon region, opposite to that of the ground X²II state. For larger internuclear distances, the A₁ ⁴Σ^? _1/2 state undergoes an avoided crossing with X₂ ²II_1/2, which causes a shoulder in the X₂ potential curve and also leads to a crossing between the A₁, and A₂ curves and large distinctions in their vibrational frequencies. The π? → σ? B²Σ^?, C²δ, and 1 ²Σ⁺ states are calculated to lie next in energy. They are all bound in the lightest of the TeX radicals, TeF, but successively lose their bonding character down the group. In contrast to oxygen monohalides, the 2²II(σ²π³ π?⁴) state has a repulsive potential curve. Electric dipole transition moments and radiative lifetimes have also been calculated for the low lying bound states in all systems. Most of them are found to be quite weak. The A^1,2 → X^1,2 spectra are dominated by parallel contributions, with the A₂ → X₁ being the strongest one. The T values for this transition are quite similar and lie in the 17–30 μs range. Radiative lifetime values for the B → X^1,2 transitions demonstrate very irregular behaviour for various, TeX radicals, due to strong admixture of A⁴Σ^? character to the X^1,2 states near the B²Σ^? potential minimum. The A^{1,2 4}Σ^? _1/2,3/2 and B²Σ^? _1/2 states of TeX (X = Cl, Br, I) still await their experimental observation.     

Li2分子自旋一致激发态a3Σ+u和b3Πu的分析势能函数的从头算

使用对称性匹配簇-组态相互作用方法首次计算了Li₂分子自旋一致激发态a³Σ⁺_u和b³Π_u的离解能、平衡几何及其谐振频率。使用最小二乘法、利用Murrell-Sorbie函数形式拟合出了Li₂分子三重态的第一激发态a³Σ⁺_u 和第二激发态b³Π_u的完整势能函数，并计算了这两个态的光谱常数 (B_e, α_e, ω_e 和 ω_eχ_e) 和力常数 (f₂, f₃和f₄)。得到了Murrell-Sorbie函数形式既适用于基态、又适用于激发态的结论。将计算得到的激发态（a³Σ⁺_u和b³Π_u）的离解能、平衡几何及其谐振频率与实验结果及其它理论计算结果进行了比较。从比较的结果中可以清楚地看出，本文的计算结果在计算精度方面有很大的改进。     

Ab initio SCF CI study of the electronic spectrum of s-tetrazine

Configuration interaction (CI) studies of ground, n→ π* and π→ π* electronically excited states are reported for s-tetrazine. The first n→ π* singlet excited state (¹ B _3u ), which is responsible for the purple-red colour of the molecule, is calculated at 2·80 eV, compared to the experimental transition energy of 2·22–2·70 eV. The singlet-triplet split of the first n→ π* states (¹ B _3u and ³ B _3u states) is calculated to be 0·76 eV.

The interaction of nitrogen lone pair orbitals (n-orbitals) is studied in terms of the ordering of the n π* excited states and found that the SCF orbital ordering is qualitatively in accord with the ordering of the n π* excited states in the CI level.

The first π→ π* excited state (¹ B _2u ) is calculated at 5·99 eV, slightly above the observed range of absorption. Numerous other high-lying singlet states as well as the triplet states have been calculated and they are used to verify several proposals relating to the excited state dynamics in the photo-physical studies of s-tetrazine.