离子对生成反应Li+I_2→Li^++I_2^-的理论研究:从头算势能面和反应几率

Theoretical Study of the Ion-pair Formation Process Li+I_2→Li^++I_2^-: Ab initio PES and Reaction Probability

采用QCISD(T)方法进行了构型优化及势能面扫描 .电荷布居分析采用QCISD ,对Li+I2 →Li+ +I-2 离子对生成反应进行了系统的从头算理论研究 :( 1)构筑了两电子态 (离子性2 B2 态和中性分子2 A1态 )的完全从头算势能面 ,找到了两电子态势能面上的最低能量反应途径及两势能曲面的交线 ,据此确定了离子态与中性分子态之间的最可几交叉半径 (Rmaxc ) ,计算了该处电子精细结构 ,得到的电子亲合能和解离能与实验光谱数据相吻合 ;( 2 )用Landau Zener公式计算了离子对生成几率 ,发现了散射共振态的存在 ,这一结果与Na +I2 →Na+ +I-2 体系非常相似 。

For ion-pair formation process Li+I 2→Li ++I - 2, the ab initio potential energy surfaces (PES) of two electronic states (ionic 2B 2 state and covalent 2A 1 state) were constructed by use of QCISD(T) method. Minimum energy reaction path on each PES and the crossing curve of the two-state PES were abstracted. According to the results, the most probable crossing radius (R max c) between the ionic and covalent states was determined, and the fine electronic structure on the crossing point was calculated. The electron affinity of I 2 molecule and the dissociation energy of I - 2 anion and the ionization potential of Li atom obtained from present PES are quite in agreement with the experimental and spectrum data. The ion-pair formation probability was calculated using Landau-Zener formula, and from it the scattering resonance state was found, which is similar to the Na+I 2→Na ++I - 2 system.