碱金属Li原子与CO分子体系相互作用势从头计算研究

摘要

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 excita-tion coupled-cluster methods with a noniterative perturbation treatment of triple excitation CCSD(T)with the AUG-CC-PVnZ basis bets, where n=2,3,4.The calculation consists of 1010 configurations.Results show that 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 with non-stand-ard T-shaped.For each basis sets,the potential energy surfaces of the complex showed a significant depend-ence on the BSSE corrections and have a high coherence with counterpoise 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 is e-nough to cause strong inelastic collisions that would prevent sympathetic cooling.%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.