超低温(uK-mK)离子+原子+原子三体复合的全维量子力学理论研究

传统分子反应动力学研究多关注两体散射如A+BC->AB+C，而对三体复合反应关注较少。后者是三个粒子碰撞形成二聚物分子并由第三个粒子带走结合能的过程，X+Y+Z->XY+Z。超低温uK-mK条件下离子+原子+原子的三体复合，是超低温化学和星际化学的重要过程，相关反应机理有待深入认识；但受限于万波尔量级的超大反应距离和基函数对三体连续态描述的不完备性等因素，传统程序化的A+BC两体散射理论无法求解此类问题。为此，项目拟以氢负离子+氦+氦及其同位素组成的三体系统为例，发展绝热超球表象方法求解非含时薛定谔方程，开展全维量子力学研究。考虑多通道耦合效应和总角动量大于零等情况，计算体系波函数、反应截面、速率常数等，分析中性分子和分子离子通道复合速率随温度的变化趋势和竞争机制；对比同位素取代体系，考察非绝热耦合、共振态等量子效应的影响。期望通过本项目研究，推动对超低温化学反应的认识并完善量子散射理论。

Traditional studies of molecular reaction dynamics mainly focused on the two-body scatterings, such as A+BC->AB+C, while less attention was paid to the three-body recombination. The latter is a three-body collision in which two atoms form a dimer molecule and the third one carries away the binding energy, X+Y+Z->XY+Z. Three-body recombination of ion+atom+atom in ultracold (uK-mK) conditions, is one of the most important processes in ultracold chemistry and interstellar chemistry, of which the relevant reaction mechanisms still need to be deeply understood. In addition, limited by the factors, such as the huge reaction distance (over tens of thousands of Bohr) and the imperfection of the basis function for the three-body continuum state, the transitional A+BC two-body scattering theory, which is well programmed, is unable to solve this type of problems. Stimulated by this, in this project, we will perform full-dimensional quantum mechanics study of the hydrogen anion+helium+helium and the isotopic substitution systems by solving the time-independent Schrodinger equation with the adiabatic hyperspherical representation method. By taking into account of the multi-channel coupling effects and the cases of total angular momentum J>0, we will calculate the scattering wave functions, the reaction cross section, and the rate constant, etc. The variation of the recombination rates of the neutral molecular and the molecular ion channels with the temperature as well as the competition mechanisms will be investigated. By comparing the isotopic substitution systems, we will further investigate several quantum effects, including the nonadiabatic coupling and the resonant quantum states, etc. By performing this investigation, it is expected to promote our understanding of the ultracold chemistry and to complete the quantum scattering theory.