Study Of The Electronic Structure And Spectroscopic Properties Of Diatomic Van Der Waals Molecules

Recently,weak interaction systems composed of atoms and small molecules have become one of the topics of studying spectroscopic properties.For van der Waals van der Waals（VDW）molecules composed of group IIb metal atoms and rare gas（Rare gas,RG）atoms,a large amount of transition and spectral information is obtained from their ground states and excited states.The experimental study of these systems in detail can allow further understanding of the VDW bond and interatomic interaction potential.Weak interactions between VDW molecules can explain the relevant dynamical processes,such as the redistribution after resonant radiation collisions,the polarization effect of electron energy transfer and collisions in the transfer,and the"semi-collision"experiments excited by VDW molecules.In this paper,coupled-cluster with single and double excitations（CCSD）,coupled-cluster with single and double excitations and perturbations connecting triple excitations（CCSD（T））methods and the equation-of-motion coupled cluster method restricted to single and double excitations（EOM-CCSD）methods are used to study the electronic structure and spectroscopic properties of singlet excited states of Zn/Cd-RG（Rare gas,RG=He,Ne,Ar,Kr,Xe,Rn）system.In addition,the multi-reference configuration interaction method is utilized to calculate Zn He molecule in detail.The main contents of this work are as follows:（1）By using the EOM-CCSD method and different basis sets,the potential energy curves of Zn-RG（RG=He,Ne,Ar,Kr,Xe）system were investigated,which including 10 singlet electronic states.Considering the energy levels of Rn and Zn atoms,the Rydberg atomic limit of Rn is not calculated in this work.Therefore,we only compute the lowest three singlet electronic states of Zn Rn.It is found that triplet excitations,basis sets and bond function have important effects on the spectroscopic constants of the ground state of Zn-RG.By using the CCSD（T）method to obtain the ground state’s energies of Zn-RG,and the singlet excited state’s excited energies are acquired by EOM-CCSD method.After the addition of the two results,the accurate PECs of the singlet excited states are acquired,thus the spectroscopic constants of excited states are received.The results are reasonable with the experimental and theoretical data in previous work,confirming the accuracy of the calculations.The transition dipole moments of C¹（47）-X¹Σ⁺and D¹Σ⁺-X¹Σ⁺are studied in detail,and the vibrational band,rotation constant and Frank-Condon factors are also calculated.（2）Considering the triplet excitations,basis sets and bond function,the EOM-CCSD method is applied to calculate the potential energy curves of the Cd-RG（RG=He,Ne,Ar,Kr,and Xe）system.Also considering the energy levels of Rn and Cd atoms,we only compute the lowest four singlet electronic states of Cd Rn.The spectroscopic constants of the Cd-RG excited states were also calculated using the same method as for Zn-RG.The computed results are closed with the experimental values.The vertical excitation energy of the excited states of Cd-RG are acquired,and the transition dipole moments of（3）¹Σ⁺-X¹Σ⁺and（4）¹Σ⁺-X¹Σ⁺of Cd-RG are studied in detail,and the Cd（5s）and Cd（6s）,Cd（5s）and Cd（5d）are forbidden transitions.The vibration band frequency,rotation constant and Frank-Condon factors of C¹（47）-X¹Σ⁺are calculated.（3）A multi-reference configuration interaction method was adopted to investigate the PECs of 9Λ-S corresponding to six dissociation limits,thus obtaining the spectroscopic constants,compared with the experimental data,the results are very precise.We take the spin-orbit coupling effects and basis set superposition error（BSSE）into account in calculation of spectroscopic information and transition properties of theΩstates.The PECs of the first excited triplet and singlet of the Zn He correlating with(1s^{2 1}S₀),Zn（4s4p ³P_J）and Zn（4s4p ¹P₁）are analyzed in detail.The electric dipole moment ofΛ-S states,the TDMs of theΩstates,the vibrational band,the rotational constant,the Frank-Condon factor of A³（47）₀₊-X¹Σ₀₊⁺and C¹（47）₁-X¹Σ₀₊⁺,the spontaneous radiation lifetime of the lower electronic states are studied.