The Investigation For The Ground State And First Excited State Of Reaction System B⁺+H₂ With Time-dependent Wave Packet Theory

Molecular reaction dynamics is a subject that studies the basic laws,characteristics and reaction mechanism of molecular reactions at the level of microscopic particles.Molecular reaction dynamics,statistical thermodynamics,structural chemistry,and quantum chemistry constitute the four cornerstones of physical chemistry.Time-dependent wave packet method is the most important method to study molecular reaction dynamics,which can give the dynamics information of three-atom reaction system intuitively.In this paper,based on the BH₂⁺ground state potential energy surface constructed by our group,the dynamic behavior of reaction B⁺（³P）+H₂（X¹∑_g⁺）→BH⁺（X²∑⁺）+H（²S）system is discussed by means of time-dependent wave packet method.The reaction probabilities for the total angular momenta J=0,10,30,40,50,70,80,100,140,150,160 and 165 in the range of collision energies 0.1 to 1.0 e V are investigated,and the reaction cross sections and thermal rate constants are also discussed.The results show that there are no significant differences between the reaction probabilities given by Coriolis coupling（CC）and centrifugal sudden（CS）approximation,but for B⁺（³P）+H₂（X¹∑_g⁺）reaction,all reaction probability curves have an oscillatory structure due to the existence of potential wells.By calculating the total reaction probabilities for different vibrational quantum numbers v=0,1（j=0）and different rotational quantum numbers j=0,1,2,3,4（v=0）,we find that vibrational excitation and rotational excitation limit the B⁺（³P）+H₂（X¹∑_g⁺）→BH⁺（X²∑⁺）+H（²S）reaction.Secondly,the time-dependent wave packet dynamics of the first excited state reaction B⁺（³P）+H₂（X¹∑_g⁺）→BH⁺（A²Π）+H（²S）are studied based on the new potential energy surface.The dependence between reaction probability and collision energy under different total angular momenta is discussed in detail.The image of reaction probability shows that the oscillation is very obvious.The reaction threshold of B⁺（³P）+H₂（X¹∑_g⁺）（v=0,j=0）increases with the increase of J,but the reaction probability becomes smaller and smaller with the increase of J.The reaction probabilities calculated by CC and CS are basically coincide,which are consistent with the results obtained in the ground state,and further confirms that CC has no influence on the reaction system.In addition,by analyzing the distribution of reaction probability under different rotation quantum number j=0-4 and vibration quantum number v=0-4 when J=0,it is found that the higher the excited state of vibration excitation,the lower the reaction threshold,which indicates that vibration excitation can greatly increase the reaction probability.The higher the excited state of rotation excitation,the lower the reaction threshold,and the more easily the reaction occurs.By comparing the integral scattering cross sections of v=0 and v=1,it can be seen that the probability of reaction occurrence increases with the increase of vibration quantum number.However,when the vibrational quantum number v increases to 2and 3,the image shows that the reaction decreases with the increase of energy.