Theoretical Study Of Scattering And Spectral Properties For Several Atoms And Molecules

In the scattering of atoms and molecules,only atoms and molecules and photons have Compton scattering,and Compton profile（CP）is obtained on the basis of Compton scattering.As a tool to detect electron momentum density,CP can reflect the distribution of electrons in each orbital of atoms and molecules truly and sensitively.Using accurate wave function to calculate the CP data can help us to understand the internal structure characteristics of atoms and molecules in advance.At the same time,the existence of s,p,d,f and other types of basis functions that constitute the wave function makes the variation of orbital wave function varied.In this paper,CP of the corresponding system is studied based on the calculation of molecular orbital wave function of several atoms and molecules in the atmosphere.Meanwhile,the spectral properties of AsBr and AsF molecules are studied by the theory of molecular orbital wave function.The specific research content of the first part can be simply expressed as the following two aspects:（1）For atoms,we use numerical integral method,calculate the H,He,Ne and Ar atoms Compton profiles,and profiles the existing experimental data,this paper compares and analyzes ruled out on the basis of different shape of error is negligible.And whether it is reasonable to calculate the profile by cartesian coordinates.（2）In the study of CP of polyatomic molecules,the simplest H₂ is firstly calculated,and then the CP of multi-orbital molecules（N₂,O₂,H₂O,CO₂）is solved.The calculation includes the direction CP of each orbital,the total direction CP and the average CP.This paper probes into the applicable range of cartesian coordinates and guesses the future research direction.The Group-VA halides are widely used in many fields such as pharmaceuticals,pigments,herbicides,preservatives,pesticides,explosive compounds,semiconductors,nanotechnology in the metallurgical industry,electronics and optics.In this paper,the spectral properties of AsF and AsBr are systematically calculated based on the molecular orbital theory and the multi-reference configuration interaction method.The research contents can be summarized as the following two aspects:（1）For the AsF and AsBr,we based on using internally contracted multi-reference configuration interaction with the addition of Davidson correction（icMRCI+Q）method,and combined with full electronic computing under gaussian basis set.Two molecular computing has two dissociation limit of 22Λ-S electronic states（AsF）and has three dissociation limit of 34Λ-S electronic state（AsBr）.At the same time,based on the potential energy curves（PECs）,we obtained the spectroscopic constants of the above molecular partially bound electron states,the main electron configuration components,permanent dipole moment（PDMs）and spin-orbit coupling matrix elements(H_so).（2）After considering the spin-orbit coupling（SOC）effect,we calculated and analyzed some important electronic state information of the two molecules in detail,including the spectroscopic constants,Frank-Compton factor（FCFs）,radiative lifetime,permanent and transition dipole moment（PDMs,TDMs）.We obtain the transition properties of AsBr molecules including TDMs FCFs and radiative lifetime.The further study of the spectra and structures of the electronic states of arsenic halide is of great significance in theory and experiment.We analyzed the pre-dissociation mechanisms of AsF molecules with various avoid crossing and intersection of a¹?,b¹Σ⁺,c’¹Π and A³Π,⁵Σ^-and ⁵Π and found that the radiative lifetime was related to the selection of the active space.