【摘要】 利用分子反应静力学的原理,确定了7L iH分子X1Σ+态的合理离解极限;使用HF、QC ISD、QC ISD(T)、B3LYP和B3P86等方法,6-311G、6-311G(d,p)、6-311G(3df,3pd)、D95V(d,p)和D95V(3df,3dp)等基组,对7LiH分子X1Σ+态的平衡核间距、谐振频率和离解能进行了优化计算,且将计算结果(平衡核间距0.160 9 nm、谐振频率1 390.51 cm-1、离解能2.474 eV)与实验结果(平衡核间距0.159 6 nm、谐振频率1 405.7cm-1、离解能2.515 eV)进行了比较,得出了包含单、双取代并加入三重激发贡献的QC ISD(T)方法为最优方法、基组6-311G(3df,3pd)为最优基组的结论.在QC ISD(T)/6-311G(3df,3pd)理论水平,对7LiH分子的X1Σ+态进行了单点能扫描,并用最小二乘法拟合出了其解析势能函数;从拟合出的解析势能函数出发,计算出了X1Σ+态的光谱常数Be,αe和ωeeχ(其值分别为7.379 cm-1、0.197 6 cm-1和21.697 cm-1),以及二阶、三阶和四阶力常数f2、f3和f4(其值分别为106.37 aJ.nm-2、-3 650.4 aJ.nm-3和112 176.2 aJ.nm-4).更多还原

【Abstract】 The reasonable dissociation limit of the X¹Σ⁺ state ⁷LiH molecule is attained by using the molecular reaction static theory.The equilibrium separation of 0.160 9 nm,the harmonic vibrational frequency of(1 390.51cm^-1)and the dissociation energy of 2.474 eV about this state are accurately calculated by using such methods as HF,QCISD,QCISD（T）,B3LYP and B3P86 with the basis sets 6-311G,6-311G（d,p）,6-311G（3df,3pd）,D95V（d,p） and D95V（3df,3pd）.Comparing the attained results with the experiments,the conclusion is gained that the QCISD（T）/ 6-311G（3df,3pd） is the most suitable for the ground-state energy calculation of ⁷LiH molecule.The whole potential energy curve for this state is further scanned at the QCISD（T）/6-311G（3df,3pd） theory level,then has a least squares fitted to the analytic Murrell-Sorbie function form,and last the spectroscopy data(B_e=7.379 cm^-1,α_e=0.197 6 cm^-1 and ω_eχ_e=21.697 cm^-1) and force constants(f₂=106.37 aJ·nm^-2,f₃=-3 650.4 aJ·nm^-3 and f₄=112 176.2 aJ·nm^-4) are calculated.更多还原