The Construction Of Globally Potential Energy Surface Of H₂O⁺ System And Studies On Its Reaction Dynamics

Due to the importance of hydrogen and oxygen-related chemical reactions in interstellar chemistry and combustion processes,this research has been of interest in the field of molecular reaction dynamics.In this paper,we used the multi-reference configuration interaction method to construct the H₂O⁺（4A"）global potential energy surface.Then,we investigated the effect of vibration and rotation excitation and Coriolis coupling on the reaction system of O（³P）+H₂⁺ and H（²S）+ OH+ reactions by means of the time dependent wave packet method.Since the previously constructed H₂O⁺ potential energy surface is not accurate enough,there is a big diference between in the calculated dynamic results and experimental values.Thus,we constructed a more accurate H₂O⁺（4A "）global potential energy surface.We used the aug-cc-pVQZ basis set,and selected 2690 ab initio energy points at the MRCI level,and then use the DMBE-SEC method to semi-emipirically correct such obtained energies.Eventually,a least-square fit was used to obtain the globally accurate potential energy surface of H₂O⁺（4A"）.O（³P）+ H₂⁺ reaction system is of great significance to the study of interstellar nebula,plasma and ionosphere.Therefore,the reaction has been paid more and more attention.Based on the H₂O⁺（12A"）fundamental potential energy surface of Paniagua et al.,we used the time dependent wave packet method to calculate the reaction probability and integral cross section of O（³P）+ H₂⁺（X2Σg+）→OH+（X3Σ-）+ H（²S）reaction.In addition,the influence of vibrational and rotational excitation on the reaction was discussed by comparing the reaction probability and integral cross section of different vibrational and rotational quantum numbers.The results show that the total reaction probability is large and there is no threshold energy,when the total angular momentum J is small.However,with the increase of the total angular momentum J,the threshold energy gradually appears and moves toward the higher energy.This is due to the fact that the reaction has a deep potential well and is an exothermic reaction.And the calculated integral cross section is consistent with the results of Paniagua et al.Since the decay of the H₂O⁺ complex basically has no effect on the initial vibrational excitation of H₂⁺,the vibrational excitation does not significantly promote or inhibit the reaction.For the O（³P）+ H₂⁺ reaction which is barrier-less,exothermic and with deep well along the minimum energy path,the effect of the rotational excitation effect on the reaction is very small.The influence of Coriolis coupling effect on the H（²S）+ OH+ reaction system was studied by using the time dependent wave packet method on the potential energy surface of H₂O⁺（12A"）.We calculated the reaction probability and integral cross section of the reaction system in both CC and CS cases.In addition,considering the CC effect,we calculated the reaction probability and integral cross section of the reactants with different vibrational quantum numbers to study the effect of vibration excitation on the reaction.The results show that the CC result is larger than that of CS because of the coupling of each channel,and the resonant structure of CC result is weaker than CS.In general,the Coriolis coupling has a great impact on this reaction.With the increas of vibrating quantum numbers,the threshold of the reaction is gradually reduced.This indicates that vibrational excitation can facilitate the progress of the reaction.In this paper,the globally accurate potential energy surface of H₂O⁺（4A "）is constructed by multi-reference configuration interaction method.We also investigated the barrier-less and exothermic reaction of O（³P）+ H₂⁺ and endothermic H（²S）+ OH+ reaction system by using the time dependent wave packet method.And we analyzed the effect of the vibrational and rotational excitation effects and the Coriolis coupling effect on the reaction.The paper is organized as follows: First,the molecular reaction dynamics is briefly introduced.Secondly,the potential energy surface theory and time-dependent wave package dynamics method are introduced briefly.Then the H₂O⁺（4A"）globally potential energy surface and the reaction dynamics of O（³P）+ H₂⁺ and H（²S）+ OH+ reaction are given.Finally,the influence of Coriolis coupling effect and vibrational excitation on H₂O⁺ reaction system are summarized.