理论研究IIB族金属二氢化物分子的基态性质

Theoretical investigation of the ground state properties of Group IIB metal dihydride molecules

基于小核能量一致性相对论赝势,采用密度泛函理论和耦合簇理论,分别在标量和二分量水平上计算研究了MH_(2)(M=Zn,Cd,Hg,Cn)分子的平衡键长和振动频率.计算结果显示,HgH_(2)和CnH_(2)的自旋轨道耦合效应较为明显.采用的8种泛函总体较好地评估了自旋轨道耦合效应.耦合簇理论计算的ZnH_(2)、CdH_(2)、HgH_(2)的键长和Σ_(u)振动频率与实验值偏差略大,这可能是由于其多参考态特性较明显.二分量PBE泛函计算的键长和Σ_(u)振动频率与实验值最接近.目前最重的CnH_(2)相关研究未见报道,研究给出了其键长和振动频率的理论值.

Based on the small-core energy-consistent relativistic pseudopotentials,the relativistic density functional theory and coupled-cluster theory(including scalar and two component)were used to calculate the bond lengths and vibrational frequencies of MH_(2)(M=Zn,Cd,Hg,Cn)molecules.The computational results indicate that the spin-orbit coupling effects are more pronounced in HgH_(2) and CnH_(2) molecules.The spin-orbit coupling effects are basically well assessed by the adopted eight functionals.The coupled-cluster calculations for the bond lengths and the Σ_(u) vibrational frequencies of ZnH_(2),CdH_(2),and HgH_(2) showed slightly larger deviations in comparison with the experimental values,which could be attributed to the multireference character of these molecules.The bond lengths and Σ_(u) vibrational frequencies computed by the two component PBE functional are closest to the experimental values.For the heaviest CnH_(2),there is no experimental or theoretical report available to date.Therefore,this work provides the theoretical values for the bond length and vibrational frequencies of CnH_(2).