The Theoretical Study Of The Ground And Excited States Properties For X₂BY?X=F,H;Y=O,S?/CH₂OO

As the basic unit of matter,atom and molecule are closely related to the micro and macro world.Molecular spectroscopy plays an important role in atomic and molecular physics.It is an important tool in the study of molecular structure,interaction between molecules and intramolecular motion.With the continuous improvement of molecular spectroscopy theory and the development of laser spectroscopy,atomic and molecular measurement and control,the research of atomic and molecular physics has stepped into a new stage.Nakatsuji et al.proposed the SAC/SAC-CI method has been applied to a variety of molecular systems of the spectrum,chemical reactions and physics,which is suitable to deal with the ground and excited states?from singlet to septet?.Recently,Wang et al.has used SAC-CI method to study the ground and the low-lying excited states of SO₂,A_SH₂,and OClO.This article is divided into five chapters.The first chapter briefly discusses atomic and molecular physics,importance of molecular spectral,related knowledge of the excited states,and relevant calculation methods of the excited states.Chapter 2introduces the basic theory of ab initio and introduces the SAC/SAC-CI method we are going to use.Chapters 3 and 4 are the most important parts of this paper.Due to the high energy density of boron,its incorporation leads to complex high temperature chemical reactions involving boron radicals.The use of boron-containing free radicals,such as low temperature initiators or rocket fuel additives,plays an important role in production and life.F₂BO is commonly used as a contaminant or as an additive,so information on the boron-containing important free radical X₂BY?X=F,H;Y=O,S? is of scientific value.Since CH₂OO was discovered in 2012,it has attracted widespread attention.It can clean the atmosphere and cool the earth.It has a profound impact on pollution control and climate change.Therefore,the study of the properties of these two molecules is both interesting and valuable.In this paper,the properties of the ground state and excited state of X₂BY?X=F,H;Y=O,S?,CH₂OO and CH₂OO⁺ are studied by the SAC/SAC-CI method in the Gaussian 09 software package.Firstly,the ground state of X₂BY free radicals are optimized by SAC method,the D95** and 6-311G?df? basis sets can afford the optimal optimization.Secondly,the excited state are obtained by SAC-CI SD-R method and SAC-CI general-R method.The vertical excitation energies,transition dipole moments and oscillation strengths are calculated.When the vertical excitation energy is less than12eV,the calculated results by SAC-CI general-R are almost same with that from SD-R method.Therefore,the first few low-excited states equilibrium geometries,rotational constants,and adiabatic excitation energies are calculated by the SAC-CI SD-R method.The equilibrium geometries and energies of the ground state for CH₂OO are calculated by the SAC method.The calculated results are in well agreement with the experimental values and the existing theoretical values in the 6-311+G** and6-311++G** basis sets.In these basis sets,the properties of the excited states are calculated,including the equilibrium geometry structures,vertical excitation energies,adiabatic excitation energies,etc.,and compared with the experimental values and theoretical values,the data is analyzed and the unknown is predicted.Finally,the calculation of its cation CH₂OO⁺,including the main configurations,vertical ionization potential,adiabatic ionization potential and so on.The fifth chapter is the summary of this paper and the prospect of further research by SAC/SAC-CI method.