阳离子XY^+(X,Y=Li,Na,K)光谱常数和分子特性计算

Theoretical Study of Spectroscopic Constants and Molecular Properties of Diatomic Cations XY^+(X,Y=Li,Na,K)

用三参数密度泛函B3LYP和耦合族理论CCSD(T)方法对6个阳离子分子XY+(X,Y=Li,Na,K)的基态进行频率和结构优化计算,获得了其平衡键长re和谐振频率ωe.进而在全空间上进行势能扫描,获得的离散势能点被拟合到SPF函数,从拟合函数中抽取相应的光谱常数,包括非谐振频率ωexe、旋转常数Be、离心畸变常数De和旋振相互作用常数αe,解离能等分子特性也进行了计算.为了研究基组对结构和光谱常数的影响,分别应用6-311++G(d,f),6-311++G(2df,2pd),6-311++G(3df,3pd)3种基组,同时验证计算结果的一致性.结果表明:CCSD(T)计算的光谱常数结果更接近实验值;6-311++G(2df,2pd),6-311++G(3df,3pd)的结果比较一致,但对个别分子离子的光谱常数ωeye和ωeze3种基组显示出了较大的差异.理论计算的结果和可获得的实验结果以及其它理论计算结果符合得比较好.

Structure, spectroscopic constants and molecular properties of cations XY ＋ （X, Y = Li, Na, K） in their ground states have been studies in detail using CCSD（T） and B3LYP. The consistency of the calculated values of spectroscopic constants and molecular properties has been tested using three basis sets 6-311 ＋ ＋ G （nd, nf） （n = 1,2,3）. The spectroscopic constants and molecular properties of these diatomic ions agree well with the experimental and theoretical values wherever available. Most of the spectroscopic constants and molecular properties of these ions are first reported. The difference of calculated results between CCSD（T） and B3LYP is mentioned.