Improved Five-Parameter Exponential-Type Potential Energy Model for Diatomic Molecules

The dissociation energy and equilibrium bond length as explicit parameters are used to establish an improved five-parameter exponential-type potential energy model for diatomic molecules. We demonstrate that the five-parameter exponential-type potential is identical to the Tietz potential for diatomic molecules. It is observed that the improved five-parameter exponential-type potential can well model the internuclear interaction potential energy curve for the ground electronic state of the carbon monoxide molecule by the utilization of the experimental values of three molecular constants.     

Relationship of the Williams-Poulios and Manning-Rosen Potential Energy Models for Diatomic Molecules

By employing the dissociation energy and the equilibrium bond length for a diatomic molecule as explicit parameters, we generate an improved form of the Williams-Poulios potential energy model. It is found that the negative Williams-Poulios potential model is equivalent to the Manning-Rosen potential model for diatomic molecules. We observe that the Manning-Rosen potential is superior to the Morse potential in reproducing the interaction potential energy curves for the \({{a}^{3} \Sigma_{{\rm u}}^{+}}\) state of the ⁶Li₂ molecule and the \({{X}^{1} \sum^{+}}\) state of the SiF⁺ molecule.     

用能量自洽法研究双原子分子离子XY+的五阶解析势能函数

将用于研究双原子分子离子XY⁺解析势能函数的能量自洽法(energy consistent method for ion XY⁺,ECMI)从三阶推广到五阶,并将双原子分子离子XY⁺的三阶解析势能函数ECMI(3)推广为五阶的解析势能函数ECMI(5),研究CO⁺的B²Σ⁺态和SO⁺的b⁴Σ^-态的解析势能函数.结果表明,CO⁺的B²Σ⁺态和SO⁺的b⁴Σ^-态的新解析势能函数ECMI(5)势与基于实验的RKR数据符合得很好,优于常用的中性双原子分子势能函数Morse势、HMS势和双原子分子离子XY⁺的ECMI(3)势在这两个离子状态下的表现.不仅如此,ECMI势给出了对原子分子碰撞等诸多研究非常重要的正确理解极限和全程势能数据.     

变分代数能量自洽法研究Li_2分子部分电子态的解析势能

在课题组前期建立的计算双核分子体系解析势能函数的代数能量自洽法(algebraic energy consistent method,AECM)的基础上,引入了经改进得到的精确研究双核分子完全振动能谱的变分代数法(variational algebraic method,VAM),获得了计算双核分子体系精确解析势能函数的变分代数能量自洽法(variational algebraic energy consistent method,VAECM)。基于有限的精确实验振动能谱数据,利用VAECM方法研究了Li_2分子1~3Δ_g,3~3Σ_g~+,1~3Σ_g~-和b~3Π_u等4个电子态的完全振动能谱和解析势能函数。获得了各电子态包含高阶的振动光谱常数、完全振动能谱、振动力常数fn和势能展开系数an,并通过可调变分参数λ最终确定了VAECM解析势能函数的具体表达形式。计算结果与其他方法的研究结果进行了比较,VAECM方法获得的振动能谱数据和势能解析表达形式能更好地描述这些电子态在渐近区和离解区的物理行为,消除了利用前期AECM方法研究这些电子态在离解区出现的非物理势垒现象。     

基于核运动效应下的H同位素双原子分子的解析势能函

在加入核运动效应修正下的Born-Oppenheimer近似电子能量的基础上, 采用QCISD(T)/ aug-cc-pvqz方法计算出H同位素双原子分子（H₂, HD, HT, D₂, DT,T₂）的势能函数参数, 获得体现H同位素分子质量差异下的势能函数。 并在此基础上导出H同位素分子的力常数和光谱数据。 同时对于OH, OD和OT分子采用QCISD/aug-cc-pvtz方法计算, 同样获得了这些分子对应的势能函数、 力常数和光谱数据。Based on the correction of the electron energy under Born Oppenheimer approximation using nuclear motion effect, the parameters of potential energy functions for hydrogen isotopic diatomic molecules (H₂, HD,HT,D₂, DT,T₂) are calculated with QCISD (T) method and aug-cc-pvqz basis set,and those potential energy functions that indicate the differences from the masses of hydrogen isotopic atoms are obtained. The force constants and spectroscopic data of those molecules are calculated as well. The potential energy functions, force constants, and spectroscopic data of the isotopic diatomic molecules OH, OD,and OT are also derived using QCISD method and aug-cc-pvtz basis set.     

Nature of the Electron Excited States and Energy Transfer in Bichromophore Coumarin Molecules

Results of experimental and theoretical research for three bichromophore molecules, trans-stilbene-CH₂-coumarin 120 (I), 4-methylumbelliferone-CH₂-UC 17, and 4-(3-fluoro)-methylumbelliferone-CH₂-UC 17 (II, III), are presented. Schemes of photophysical processes in the bichromophore molecules based on quantum chemical calculations by the INDO method and theory of radiationless transitions in polyatomic organic molecules are suggested. After optical excitation to the strong donor absorption band, the fast internal conversion processes develop there. As a result, the molecule is found in the S ₁ ^* -state localized on the acceptor moiety. It is shown that a mechanism of intramolecular transfer energy in bichromophores different from that proposed by Förster may be realized. Excitation energy, initially located on D, will be transferred from the donor moiety to the acceptor chromophore in convenience of the internal conversion process. The intramolecular electronic energy transfer from energy donor to energy acceptor may be interpreted as the internal conversion process. The rate constants of internal conversion are calculated.     

双原子分子电子能量损失谱的解谱方法

介绍一种双原子分子电子能量损失谱的解谱方法,在利用已知的双原子分子光谱信息及理论计算的Franck-Condon(FC)因子的基础上,通过二次函数调整整个电子态振动强度的轮廓,减少拟合过程中的待定参数个数,降低对FC因子精确性的要求,提高拟合的精度和可信度.用Mathematica语言编写基于以上方法的数据处理程序,改进算法,提高了软件的运行效率.利用该软件处理氢分子的电子能量损失谱,得到氢分子不同电子态的振动跃迁的截面信息,所得结果与以前的实验结果符合很好.     

An Accurate Calculation of Potential Energy Curves and Transition Dipole Moment for Low-Lying Electronic States of CO

In this paper, potential energy curves for the X 1 Σ+ , a3 Π, a′3 Σ+ , d3 , A1 Π and I 1 Σ states of CO have been calculated using complete active space self-consistent field and multi-reference configuration interaction methods. The calculations have been performed at 108 nuclear separations from 0.7 to 4.0 A by the aug-cc-PV5Z basis set. Spectroscopic constants for the six low-lying electronic states are found in good agreement with experimental data. The vibrational states of the X1Σ+ and A1Π states are also calculated, which are reliable and accurate by comparison with the experimental data and the other theoretical values. The transition dipole moment (TDM) shows that the TDM of the two states (X1Σ + A1Π) are reduced strongly with increase of bond length.     

Resonance CARS Study of Electronic Excited Molecules

Abstract

There has been much progress in the vibrational spectroscopic study of short-lived chemical species and electronic excited states in the last decade [1, 2]. Most of those studies employed Raman scattering method by recourse to the resonance enhancement associated with the transient electronic absorption. TR³ is now widely known aB standing for “Time-Resolved Resonance Raman” spectroscopy.     

普适性双原子分子解析势能函数的研究

提出了一种构造解析势能函数的新方法,由此得到了一种既适用于中性双原子分子又适用于带电双原子分子离子的解析势能函数。本文用八种基本类型的双原子分子——同核中性基态双原子分子Na₂-X1Σ+_g,同核中性激发态双原子分子C₂-A1Π_u,同核带电基态双原子分子离子He+₂-X2Σ+_u,同核带电激发态双原子分子离子N+₂-B2Σ+_u,异核中性基态双原子分子NaLi-X1Σ+_g,异核中性激发态双原子分子BH-B1Σ+,异核带电基态双原子分子离子(BC)--X3Π,异核带电激发态双原子分子离子(CS)+-A2Π等共21个算例对势能函数进行了验证并与RKR (Rydberg-Klein-Rees)实验数据进行了比较,计算结果与RKR数据符合很好。     

双原子分子电子光谱的振动结构分析

从电子振转能级的光谱项出发,分析了双原子分子电子振动谱带序和电子振动谱带列的规律,并归纳出德兰德斯表(Deslandres table)及其主要性质。以C₂分子电子振动光谱的斯簧谱带系作为实例,说明了如何对电子振动光谱的测量值进行标识,并将它们按振动结构规律整理成德兰德斯表,从而获得有关分子光谱不同态的非谐性常数、振动频率等重要参数以及任意谱带的波数公式。     

水分子F态超快动力学：时间分辨光电子能谱研究

本文利用双光子激发和时间分辨的光电子成像技术研究了水分子■态的超快动力学.这是首次对水分子■态进行时间分辨的实验研究.水(重水)分子■和■态的寿命分别为1.0±0.3(1.9±0.4)和10±3(30±10)皮秒.我们提出■态主要通过非绝热耦合内转换到■态,而■态通过科里奥利相互作用耦合到■态.     

Possibilities of Distributive Gaussian sp-Functions for Calculating the Correlation Energy of Molecules in the Ground and Excited States

Optics and Spectroscopy - The possibilities of distributive bases from Gaussian sp-functions for calculating the correlation energy of molecules in the second order (Е(2)) of the...     

Murrell-Sorbie势能参数与双原子分子光谱数据的关系研究

研究了Murrell-Sorbie势能参数与双原子分子光谱数据的关系.根据光谱数据编程计算了卤化氢分子的力常数和Murrell-Sorbie势能参数.反过来,运用ab initio和非线性最小二乘法拟合出了HF分子的Murrell-Sorbie势能函数和势能参数;并由此计算了HF分子的光谱数据,与实验光谱数据符合较好.这对难以获得实验光谱数据的双原子分子和离子的动力学研究有一定的参考价值.     

Consideration of Electronic-Vibrational Interactions in Calculations of Electronic Transition Moments for Diatomic Molecules

Two different approaches to the determination of the dependence of the electronic transition moment on the internuclear distance, M_e(R), are considered. It is shown that M_e(R) dependences obtained by ab initio and semi-empirical methods take into account electronic-vibrational interactions in a various manner. In semi-empiral methods these interactions are take into account to a greater degree, than in non-empirical quantum-mechanical methods which do not include nonadiabatic corrections. A system of concepts, which allows to unite the information obtained in two different, mutually complementing ways, is considered in the paper.     

Potential Energies, Permanent and Transition Dipole Moments for Numerous Electronic Excited States of NaK

Recent experimental works have been devoted to the spectroscopy of highly excited states of NaK, confirming the accuracy of our previous calculations [S. Magnier and Ph. Millié, Phys. Rev. A: Gen. Phys. 54, 204 (1996)] of spectroscopic constants and potential curves. Among them, [E. Laub, I. Mazsa, S. C. Webb, J. La Civita, I. Prodan, Z. J. Zabbour, R. K. Namiotka, and J. Huennekens, J. Mol. Spectrosc. 193, 376 (1999)] have deduced from their measurements the variation of the transition dipole moment with the interatomic distance for the transition X(1)Sigma+ --> (3)(1)Pi. They have shown that a large discrepancy was observed with the previous ab initio calculations currently used as a guide for spectroscopic experiments. Upon request of several experimentalists, we have computed again potential curves for electronic states correlated up to Na(4p) + K(4s) as well as relevant permanent and transition dipole moments. We present extensive predictions for the electronic structure of NaK (potential energies, dipole moments) for which numerical data have been listed in a data base available as supplementary data. Copyright 2000 Academic Press.     

Excited Electronic States of Pyrene and some Azapyrenes

Pyrene and three azapyrenes have been studied by means of linear and magnetic circular dichroic spectroscopy. As a result, an improved understanding of the lower excited states has been reached, and a simple relation has been found between structure and MCD sign of the first two transitions in the azapyrenes.     

Energy Levels of Doubly Excited States in Argon

Term energies of doubly excited states in argon and argon ions have been determined using single-configuration Hartree-Fock calculation. The energies calculated for KL3s3p⁶nl and KL3s⁶3p⁴nln1 states of Ar show a fairly good agreement with the experimental results obtained by various techniques. However, for Ar+, Ar²+, Ar²+ and Ar³+ states there are no experimental data available in the literature for comparison.     

Excited Binomial States and Excited Negative Binomial States of the Radiation Field and Some of Their Statistical Properties

We introduce excited binomial states and excited negative binomial states of theradiation field by repeated application of the photon creation operator on binomialstates and negative binomial states. They reduce to Fock states and excitedcoherent states in certain limits and can be viewed as intermediate states betweenFock states and coherent states. We find that both the excited binomial statesand excited negative binomial states can be exactly normalized in terms ofhypergeometric functions. Base on this interesting characteristic, some of thestatistical properties are discussed.     

Collisional Energy Transfer of Highly Vibrationally Excited Polyatomic Molecules. The Effect of Excited Molecule Complexity

Collisional relaxation was probed by CO₂ laser activated delayed fluorescence. The experimental information was adopted to determine the average energies transferred per collision (ΔE) from highly vibrationally excited polyatomic molecules to parent collider. The values of (ΔE) decreased with increasing the number of atoms in the excited molecules in line: biacetyl, acetophenone, benzophenone, antraquinone. The dependences of (ΔE) on the number of factors such as: 1) the average vibrational energy residing in the vibrational modes of excited molecules; 2) the potential of intermolecular interaction; 3) the reduced mass, and others were analyzed in details. The general interplay was noticed between (ΔE) and the molecular parameters which determined the increasing interaction strength and the decreasing energy transfer efficiency due to the adiabatic constraints on the energy transfer.