Agn(n=2～10)团簇的几何结构和电子特性

应用密度泛函理论中B3LYP/LANL2DZ 方法优化计算并分析了Agn(n=2～10)团簇的基态几何结构及电子性质.同时计算和讨论了银团簇的原子化能、能级分布、能级间隙、电子亲和能和电离势,所得理论计算值与实验值符合较好.研究结果表明:银小团簇的结构不同于块体,且随团簇尺寸大小而相应变化,原子化能和电子亲和势随原子尺寸的增加而增加,团簇的费米能级、电子亲和势和电离势随团簇大小变化具有明显的奇偶振荡特性,并对此作了分析.团簇的电子性质和几何结构之间的密切关系及其随团簇尺寸大小变化的规律,可以从理论上确定团簇的最稳定结构,并可对实验观测结果做出解释.     

Cu2团簇分子的垂直电离势和电子亲合能的理论计算

利用含有电子相关效应校正的密度泛函理论DFT中的 B3LYP 方法,选择LANL2DZ双ζ基组,对Cu2分子及其分子离子的势能函数进行理论研究.计算得到Cu2,Cu+2,Cu2+2,Cu-2和Cu2-2基电子状态分别是1Σg+,2Σg, 1Σu, 2Σu和1Σg,导出了相应的分子及分子离子的解析势能函数,并计算出Cu2分子的垂直电离势和电子亲合能.计算结果与实验值吻合得较好.     

钇二氢化反应热力学函数的研究

用密度泛函方法B3LYP/SDD/6-311＋＋G**计算了YH₂的微观性质. 并用分子总能量中的振动能E_v代替固态能量0705212, 振动熵S_Ev代替固态熵的近似方法, 以及考虑到电子能量的变化, 计算了固态YH₂(D, T)的焓H和熵S, 得到不同温度下Y与H₂, D₂, T₂反应的ΔH^⊖, ΔS^⊖, ΔG^⊖及氢化反应平衡压力, 导出了与温度的依赖关系. 计算结果表明, YH₂(s)的生成热为199.25 kJ•mol^－1, 与实验值210.00及 225.94 kJ•mol^－1非常接近, 说明近似方法的正确性.     

The theoretical study on the potential energy curves for X^1 ∑^＋, A^1 ⅡI and C^1 ∑^- states of SiO molecule

This paper applies the symmetry-aziapted-cluster/symmetry-adapted-cluster configuration-interaction （SAC/SACCI） method to optimize the structures for X^1∑^＋, A^1 Ⅱ and C^1 ∑^- states of SiO molecule with the basis sets D95＋＋, 6-311＋＋G and 6-311＋＋G^＊＊. Comparing the obtained results with the experiments, it gets the conclusion that the basis set 6-311＋＋G^＊＊ is most suitable for the optimal structure calculations of X^1.∑^＋, A^Ⅱ and C^1∑^- states of SiO molecule. The whole potential energy curves for these electronic states are further scanned by using SAC/6-311＋＋G^＊＊ method for the ground state and SAC-CI/6-311＋＋G^＊＊ method for the excited states, then use a least square method to fit Murrell~Sorbie functions, at last the spectroscopic constants and force constants are calculated, which are in good agreement with the experimental data.     

SAC-CI方法研究甲基乙烯基硅酮分子激发态1 1A’’, 1 1A’, 2 1A’’结构与性质

采用对称性匹配簇/组态相互作用(symmetry adapted cluster－configuration interaction, SAC－CI)方法, 在6-311++g**基组水平上优化了甲基乙烯基硅酮分子的前三个单激发态1 1A’’, 1 1A’, 2 1A’’的平衡几何结构, 比较三个激发态的电荷分布, 最高占据轨道, 最低空轨道, 能隙等结构特性. 研究发现, 1 1A’ 态能隙差最小, 电子容易发生跃迁. 计算了三个单重激发态相应的振动光谱, 得出其振动模式. 从甲基乙烯基硅酮分子激发态结构特性, 电荷分布, 极强位置振动模式等方面分析了其断键机制.     

Si3O cluster: excited properties under external electric field and oxygen-deficient defect models

This paper investigates the excited states of Si₃O molecule by using the single-excitation configuration interaction and density functional theory. It finds that the visible light absorption spectrum of Si₃O molecule comprises the yellow and the purple light without external electric field, however all the visible light is included except the green light under the action of external electric field. Oxygen-deficient defects, which also can be found in Si₃O molecule, have been used to explain the luminescence from silicon-based materials but the microstructures of the materials are still uncertain. Our results accord with the experimental values perfectly, this fact suggests that the structure of Si₃O molecule is expected to be one of the main basic structures of the materials, so the oxygen-deficient defect structural model for Si₃O molecule also has been provided to research the structures of materials.     

First-Principles Calculations of Elastic Properties of LaNi5 Compound

The equilibrium lattice constants, temperature dependence of bulk modulus, the pressure dependence of the normalized volume V/V0, elastic constants Cij and bulk modulus of LaNi5 crystal are obtained using the firstprincipies piane-wave pseudopotential method in the GGA-PBE generalized gradient approximation as well as the quasi-harmonic Debye model. We analyse the relationship between bulk modulus and temperature up to 2000 K and obtain the relationship between bulk modulus B and pressure at diFFerent temperatures. It is found that the bulk modulus B increases monotonously with increasing pressure. Moreover, the pressure dependences of Debye temperatures and the pressure derivatives of lattice constants are also successfully obtained. The calculated results are in agreement with the experimental data and the other theoretical results.     

曲率对机翼边界层二次失稳影响

采用非线性抛物化扰动方程(NPSE)计算了层流机翼NLF0415(2)在几个工况下横流涡的非线性发展, 应用Floquet理论分析了横流涡的二次失稳. 较系统地分析了后掠机翼在多种参数下表面曲率对其流动稳定性的影响. Haynes证明曲率对于横流在线性稳定性计算(LST)和非线性抛物化扰动方程计算中(NPSE)都起着非常明显的稳定作用; 然而, 该文计算结果表明, 曲率在二次失稳计算中影响不大.      

The theoretical study on the potential energy curve for X~3△ state of TiO molecule

This paper applies the density functional theory method to optimise the structure for X ³Δ state of TiO molecule with the basis sets 6-31G, 6-31++G and 6-311G^**. Comparing the attained results with the experiments, it obtains the conclusion that the basis set 6-31++G is most suitable for the optimal structure calculations of X ³Δ state of TiO molecule. The whole potential energy curve for the electronic state is further scanned by using B3P86/6-31++G method for the ground state, then it uses a least square fitted to Murrell--Sorbie functions, at last it calculates the spectroscopic constants and force constants, which are in better agreement with the experimental data.     

光功能导向的SiNN分子电致发光特性研究

采用优选出的密度泛函B3P86/cc-PVTZ方法对SiNN分子进行了基态结构的优化,然后使用含时密度泛函方法(Time-dependent density functional theory,TDDFT)计算了SiNN分子前7个激发态的激发能,吸收谱,跃迁振子强度等激发特性,进而在得到不同外电场下SiNN分子的基态稳定结构的基础上,研究了外电场作用下SiNN分子的激发特性.与无电场时的激发特性进行比较发现SiNN分子的激发能,吸收谱,跃迁振子强度在外电场作用下变化明显,特别是加场后使原来跃迁禁戒的能级之间发生了跃迁,出现了紫光区的376～401 nm波长的吸收谱,电子在各能级之间的跃迁能力也发生了很大改变.同时对SiNN分子可见光谱的产生机理也进行了分析,经理论分析发现SiNN分子有可见光波段的发射谱且数值与实验测量结果非常吻合.