HX_2^+(X=Cl,Br)离子的结构与HBr_2^+离子的势能函数  

Structures of the HX_2^+(X=Cl,Br) Ions and Analytic Potential Energy Function of the HBr_2^+ Ion

作　　者：刘岩[1] 张现周[2] 罗志环[1] 黎永耀[1] 

机构地区：[1]华南农业大学理学院应用物理系,广东广州510642 [2]河南师范大学物理与信息工程学院,河南新乡453002

出　　处：《信阳师范学院学报（自然科学版）》2009年第4期518-521,共4页Journal of Xinyang Normal University(Natural Science Edition)

基　　金：广东省自然科学基金项目(07300793);华南农业大学校长基金项目(4900-K06169)

摘　　要：选取密度泛函(B3LYP)方法,采取6-311++G(2df,2pd)基组对单态HCl2+与HBr2+离子可能的几何构型进行了优化计算,并求得了Cl2与Br2的质子亲和能及Cl—CIH+与Br—BrH+的键分离能.得到HCl2+离子最稳态为Cs构型,电子态为1A′,平衡核间距为RCIH=0.1315nm,RClCl=0.2022nm,键角∠HClCl=99.4°.HBr2+离子最稳态为Cs构型,电子态为1A,平衡核间距为RBrH=0.1452nm,RBrBr=0.2328nm,键角∠H-BrBr=97.5°,离解能为De=8.208eV,Br—H键伸缩振动频率为2399cm-1,H—Br—Br键弯曲振动频率为706cm-1,Br-Br键伸缩振动频率294cm-1.并首次采用多体项展式理论推导出了基态HBr2+离子的解析势能函数.对应的等值势能图准确再现了HBr2+离子的平衡结构及其离解能;并可由势能图观察到Br(2Pu)+HBr+(X2Πi)→HBr2+(X1A′)反应通道上出现一个鞍点,其位置在RBrBr=0.42nm,RHBr=0.16nm,∠HBrBr=97.5°,V=-5.5eV,垒高约0.53eV.Using density functional（B3LYP） method and the 6-311 ＋ ＋ G（2df,2pd） basis set,the possible config- urations of the single state HCl2＋ and HBr2 ions have been optimized, and the proton affinity of Cl2 and Br2, the bond dissociation energy of Cl--CIH ＋ and Br---BrH ＋ have been calculated. The results show that the ground state of HCl2＋ ion has C, symmetry and is in the 1A＇ state. The parameters of structure are RCIH =0. 131 5 nm,Rclcl =0. 202 2 nm, ∠HC1C1 =99.4°. The results also show that the ground state of HBr2 ion has Cs symmetry and 1A＇ state. The parame- ters of structure are RBrH =0. 145 2 nm,RBrBr =0. 232 8 nm, / HBrBr =97.5 ° ,Dc = 8. 208 eV and the harmonic fre- quencies of HBr2＋ are 2 399 cm -1 of Br--H stretching vibration,706 cm -1 of H-Br-Br bending vibration and 294 cm -1 of Br-Br stretching vibration. The potential energy function of HBr2＋ ion has been derived for the first time from the many-body expansion theory. The analytical potential energy function describes correctly the ground-state structure and dissociation energies. Molecular reaction statics of 2 Br （ Pu ） ＋ HBr ＋（X2∏i）→HBr＋ （ X1 A＇ ） based on the potential en- ergy function is discussed briefly.

关 键 词：HCl2+ HBr2+ 密度函数理论 结构性质 多体项展式理论 解析势能函数 

分 类 号：O641[理学—物理化学]