碱金属Li原子与CO分子体系相互作用势从头计算研究

采用三重激发项校正CCSD的CCSD(T)方法和AUG-CC-PVnZ(n=2,3,4)基组,优化了CO基态分子结构,并计算了碱金属Li原子与CO分子的相互作用势,共1010个构型势能点得到体系的势能面.结果表明:同一方法下,不同基组得到的CO基态分子的键长、能量等均与实验符合很好.Li-CO势能面体现较小的各向异性势,存在两个势阱,且都为非严格T型结构;基组重叠误差(BSSE)对相互作用势的影响比较明显,采用CP方法(Counterposie method)消除基组重叠误差,不同基组计算的相互作用势显示较好一致.体系各项异性势势阱值远高于CO基态分子转动常数,使得碰撞产生强烈的非弹性碰撞,这将阻止协同冷却制备超冷分子.

An ab intito potential energy surface of alkali-metal lithium with CO molecule

The carbon monoxide ground state molecule has been calculated and the interaction potential energy surfaces of the ground electronic state of the Li-CO complex have been studied by the single and double excitation coupled-cluster methods with a noniterative perturbation treatment of triple exciation CCSD(T) with the AUG-CC-PVnZ basis bets, where n=2,3,4. There are calculation consists of 1010 configurations. Results show the equilibrium structure, total energy, et al of CO ground state molecule are in excellent agreement with the experimental results used by CCSD(T)/AUG-CC-PVDZ, CCSD(T)/AUG-CC-PVTZ and CCSD(T)/AUG-CC-PVQZ basis bets. The anisotropy potential energy surfaces are two potential wells which are non-standard T-shaped. For each bsais sets, the potential energy surfaces of the complex are showed a significant dependence on the BSSE corrections and have a high coherence with counterposie method. The absolute well depths for the Li-CO complex are much larger than the rotational constant of CO, and the anisotropy of the potential are enough to cause strong inelastic collsisions that would prevent sympathetic colling.