The Research On The Excited States Of The Spectroscopic Properties Of BSe?NTe,and CBr Radical

Based on the Born-Oppenheimer approximation,molecular potential energy function could well describe the molecule properties in the full space.With the aid of potential energy function,we can study the electronic structure,electronic character,transition properties and spectral characteristic of molecules.The ab initio calculation was carried out by the MOLPRO 2010 program package.At each given nuclear separation,the spin-restricted Hartree-Fock(RHF)method is chosen to obtain the wavefunction of the ground state molecule.Then the state-averaged complete active space self-consistent field(SA-CASSCF)calculations are performed with RHF orbitals as the initial guess.Finally,the correlation energy of electronic state is calculated by the multi-reference configuration interaction(MRCI)method using the CASSCF energy as reference energy.In addition,the Davidson modification(+Q)is taken into consideration to correct the size consistency.The spin-orbit coupling effect was taken into account via the states interaction method.The potential energy curves of the ?-S states and ? states are plotted with the aid of the avoided crossing rule(non-crossing rule).For the calculated bound states,the spectroscopic constants are determined by numerical solution of the nuclear Schr?dinger equation with LeRoy's Level 8.0 Program.By taking into the expectation and transition values which using the MRCI wave function,the dipole moments and transition dipole moments for the selected ?-S states and the ? states are computed.And we investigate the relationship between dipole moments functions and the polarity of molecule.Finally,the Franck-Condon factors(FCs),Einstein emission coefficients(A??,???)and the corresponding radiative lifetimes of the selected transitions were calculated.Moreover,we evaluate the phenomenon that the avoided crossing has effect on ? electronic states and its transitions properties after taking into account the spin-orbit coupling(SOC)effect.This work consists of six chapters.The chapter one introduces significance and background of the work.The chapter two describes the theoretical method,including HF-SCF,CASSCF,MRCI and state interaction method.The chapter three discusses the 15 ?-S electronic states and 32 ? states of BSe,and the transitions properties is considering as well.The chapter four discusses 28 ?-S electronic states and 30 ? states of NTe,and we investigate the relationship between ?-S states dipole moments functions and the polarity of molecule.The relationships of Franck-Condon factors(FCs),Einstein emission coefficients(A??,???)and the intensity distributions among the bands of the selected transitions is analyzed.The chapter five discusses the 28 ?-S electronic states belong to the lowest three dissociation limits and 45 ? states of CBr,then the electronic structure and transitions properties being calculated.We also evaluate the phenomenon that the avoided crossing has influence on ? electronic states after taken into account spin-orbit coupling(SOC)interaction.The chapter six is the conclusions of the current work.