分子冷却到足够低温度是应用于量子计算、量子模拟和精密测量的前提。激光冷却原子已很广泛，但能冷却的分子、尤其是多原子分子还相当有限，因为设计分子激光冷却方案需要分子多个电子态的势能面、振转能级和跃迁偶极矩等方面的精确数据。相关数据原则上可由从头计算方法获得，然而高精度计算多个电子激发态势能面和电子态间跃迁偶极矩同样面临挑战。本项目将基于多参考组态相互作用和相对论量子力学等框架，考虑自旋-轨道耦合等非绝热效应，发展高精度同时计算多个电子态势能面和跃迁偶极矩的方法，获得电子基态和激发态相互关联的势能面和跃迁偶极矩，并构建其解析表达式。在此基础上采用量子动力学方法、通过求解分子核运动薛定谔方程，计算各电子态振转能级、Franck-Condon因子、辐射寿命及激光与分子相互作用回复力，从而建立激光冷却方案、确定激光冷却可达到的预期温度和所需的激光波长等物理量，为激光冷却相应分子实验方案提供理论依据。

The satisfactory cold of the molecule is the precondition for the quantum computation, the precise measurement and quantum simulation of the molecule. Laser cooling method has been widely used for cold atoms. However, only a few molecules, especially for polyatomic molecules, have been cooled because laser control molecule must be based on the precise potential energy surfaces (PESs), vibrational and rotational energy levels (VRELs) and transition dipole moments (TDMs) of several electronic states. The cooling scheme of a molecule is impossible for a new molecule which precise information on electronic properties is unknown. Generally, the information could be obtained from ab ignition calculations. However, the precise calculations of the PESs, TDMs for several electronic states of the molecule at the same time are also very challenge work. The present project will develop a precise calculational method to obtain the PESs and TDMs for molecular several electronic states as well as their analytical expressions based on the multi-reference configuration interaction, the relativistic quantum mechanics and the diabatic effect with spin-orbit coupling. Then, the VRELs, Franck-Condon factors, radiative lifetimes and the recoil forces of the object molecule are determined by the aid of solving the Schrödinger equation of the molecular nuclear movement by quantum dynamics calculations. Based the results, we will construct the cooling scheme, and predict the expected cooling temperature and the wavelength of the laser to perform the cooling. The findings can provide an initial scheme to obtain the cold molecule experimentally.