SiX2(X=H,F)分子的结构与势能函数  

The structure and potential energy function investigation on SiX_2(X=H,F) molecules

作　　者：蒋利娟[1,2] 刘玉芳[1] 刘振中[1] 韩晓琴[1] 

机构地区：[1]河南师范大学物理与信息工程学院,新乡453007 [2]新乡学院物理系,新乡453003

出　　处：《物理学报》2009年第1期201-208,共8页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:10574039);教育部科学技术研究重点项目(批准号:206084);河南省创新型科技人才队伍建设工程(批准号:084100510011);河南省高等学校杰出科研人才创新工程(批准号:2006KYCX002)资助的课题~~

摘　　要：应用QCISD/6-311++G(3df,3pd)和B3P86/6-311++G(3d2f)对SiH2,SiF2的结构进行了优化,优化出SiH2分子的稳定构型为C2v,电子态为1A1,其平衡核间距Re=0.15149nm、键角∠HSiH=92.5025°、离解能为3.7098eV.SiF2分子的稳定构型为C2v,电子态为1A1,其平衡核间距Re=0.16014nm、键角∠FSiF=100.7079°、离解能为14.1391eV.并对它们的力常数及谐振频率进行了进一步的计算.在推断出SiX2(X=H,F)的离解极限的基础上,应用多体展式理论方法,导出了基态SiX2(X=H,F)分子的解析势能函数,该势能表面准确地再现了SiX2(X=H,F)分子的结构特征和能量变化.分析讨论势能面的静态特征时得到SiH+H→SiH2反应中存在鞍点,活化能为192.971kJ/mol,为有阈能的反应.而SiF+F→SiF2反应中没有鞍点,是无阈能的反应.Using the QCISD/6-311＋＋G（3df,3pd） and B3P86/6-311＋＋G（3d2f） respectively,the possible ground-state structures of SiH2 and SiF2 molecules have been optimized.The results show that the ground state of SiH2 molecule is of C_ 2v symmetry and in the 1A1 state,whose angle,equilibrium nuclear distance and dissociation energy are 92.5025°,0.15149 nm and 3.7098 eV,respectively,The results also show that the ground state of SiF2 molecule is of C 2v symmetry in the 1A1 state,whose angle,equilibrium nuclear distance and dissociation energy are 100.7079°,0.16014 nm and 14.1391 eV,respectively,and their harmonic frequencies and force constants have been calculated.The present paper correctly determines the dissociation limits based on group theory and atomic and molecular reactive statics（AMRS）.Analytical potential energy functions for the ground states X1A1 of SiX2（X=H,F） have been derived using many-body expansion method.The structure and energy of SiX2（X=H,F） can correctly reappear on the potential surface.Molecular reaction kinetics of SiH＋H and SiF＋F based on the potential energy functions is discussed briefly.

关 键 词：SiH2 SiF2 多体项展式理论 势能函数 

分 类 号：O561.1[理学—原子与分子物理] TG146.11[理学—物理]