AlI,AlI_2分子的结构与从头计算

应用密度泛函B3P86方法,采用DGDZVP基组对AlI(X1∑+)进行了理论计算,得到它的微观几何结构,力学性质和光谱性质,结果表明AlI的平衡核间距为0.258 56 nm,基态离解能为4.006 eV,谐振频率为308.361 7 cm-1,并得到它的Murrell-Sorbie势能函数.应用密度泛函B3P86/3-21G,优化出AlI2(X2A1)分子稳定构型为C2v,其平衡核间距Re=0.258 88 nm,∠IAlI=122.432 5°、离解能为5.278 4 eV,同时计算出了力常数及谐振频率.在推断出AlI2的离解极限此基础上,应用多体展式理论方法,导出了AlI2基态分子的解析势能函数,该势能面准确地再现了AlI2(X2A1)分子的结构特征和能量变化.

Structure and Ab initio Calculation on AlI and AlI2 Molecule

Equilibrium geometry,force property and spectroscopy property of AlI(X~1 ∑~+ )molecule have been calculated using the B3P86 method with the basis set DGDZVP.The equilibrium nuclear distance,dissociation energy and harmonic frequency are 0.258 56 nm,4.006 eV and 308.361 7 cm~(-1) respectively,in good agreement with experimental values.The Mur-rell-Sorbie potential function of AlI(X~1 ∑~+ ) molecule is obtained.Using the B3P86 method with the basis set 3 -21G,the present work has optimized the equilibrium geometry for the ground state X~2A_1 of AlI_2,which is C_(2v) I—Al—I,whose angle,equilibrium nuclear distance and dissociation energy are 122.432 5°,0.258 88 nm and 5.278 4 eV respectively.And its harmonic frequencies,force constants also 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 function for the ground state X~2 A_1 AlI_2 of has been derived using many-body expansion method.The structure and energy of AlI_2 can correctly reappear on the potential surface.