Zhao Yanliang, Wang Meishan, Yang Chuanlu, Ma Xiaoguang, Li Jing
School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China.
School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2018 Feb 15;191:382-388. doi: 10.1016/j.saa.2017.10.016. Epub 2017 Oct 10.
The construction of the complete third and the semi-diagonal quartic force fields including the anharmonicity of the ground state (X˜A) for yttrium dicarbide (YC) is carried out employing the vibrational second-order perturbation theory (VPT2) in combination with the density functional theory (DFT). The equilibrium geometries optimization, anharmonic force field and vibrational spectroscopic constants of YC are calculated by B3LYP, B3PW91 and B3P86 methods. Aug-cc-pVnZ (n=D, T, Q) and cc-pVnZ-PP (n=D, T, Q) basis sets are chosen for C and Y atoms, respectively. The calculated geometry parameters of YC agree well with the corresponding experimental and previous theoretical results. The bonding characters of YC or CC are discussed. Based on the optimized equilibrium geometries, the spectroscopic constants and anharmonic force field of YC are calculated. Comparing with the spectroscopic constants of YC derived from the experiment, the calculated results show that the B3PW91 and B3P86 methods are superior to B3LYP for YC. The Coriolis coupling constants, cubic and quartic force constants of YC are reasonably predicted. Besides, the spectroscopic constants and anharmonic force field of YC (X˜A) and YCC (X˜A) are calculated for the first time, which are expected to guide the high resolution experimental work for YC and its C isotopologues.
采用振动二阶微扰理论（VPT2）结合密度泛函理论（DFT），构建了包括碳化钇（YC）基态（X˜A）非谐性的完整三阶和半对角四次力场。通过B3LYP、B3PW91和B3P86方法计算了YC的平衡几何结构优化、非谐力场和振动光谱常数。分别为C和Y原子选择了Aug-cc-pVnZ（n = D、T、Q）和cc-pVnZ-PP（n = D、T、Q）基组。计算得到的YC几何参数与相应的实验结果和先前的理论结果吻合良好。讨论了YC或CC的键合特征。基于优化后的平衡几何结构，计算了YC的光谱常数和非谐力场。与实验得到的YC光谱常数相比，计算结果表明B3PW91和B3P86方法对于YC优于B3LYP。合理预测了YC的科里奥利耦合常数、三次和四次力常数。此外，首次计算了YC（X˜A）和YCC（X˜A）的光谱常数和非谐力场，有望指导YC及其C同位素的高分辨率实验工作。
