The Study Of Geometric Structure And Spectral Properties Of Molecules Containing Magnesium

Study on molecular structures and properties are one of the research hotspots in atomic and molecular physics,theoretical chemistry and other areas.Moreover,the molecular potential energy function can fully describe the relevant properties of the molecular system,such as molecular energy,geometric configuration and so on.The atom collisions and scatterings,as well as the spectral properties of electronic transitions,can also be analyzed by potential energy functions.In addition,the study of the molecular potential energy function can provide theoretical guidance for molecular spectral analyses.Therefore,the molecular potential energy function plays a vital role in both theoretical research and experimental applications.Ultracold atoms has become the frontier area of today's scientific researches.Related studies show that diatomic molecules formed by an alkali metals atom and an alkaline earth metals one have extensive applications in laser cooling.Among them,there is no theoretical or experimental report on the feasibility of NaMg as ultracold molecules,and there is no data about its molecular structure and spectrocopy.MgS is not only an important component of the nebula material,but also a material for manufacturing the electrode of energy storage battereis.Although MgS has been widely studied,its cation MgS~+is rarely reported.Therefore,studies of these two molecular systems have practical significance.In this paper,the electronic ground states and low-lying excited states of the MgS~+and NaMg systems have been studied by utilizing the multireference configuration interaction(MRCI)method combined with the all-electron relativistic augmented correlation-consistent polarized core-valence quintuple-zeta basis set(aug-cc-pCV5Z-DK).The Murrell-Sorbie potential function has been used to fit the single-point energy data to obtain analytical potential energy functions for these two systems.The vibrational energy levels and the rotational constants of the low-lying electronic states of the two species are derived by numerically solving the one-dimensional Schr?dinger equation of nuclear motion with the aid of the LEVEL 8.0 program package.Furthermore,the data related to the ground and low-lying states of the two systems are determined,such as system energy,structural parameters,spectroscopic constants,permanent dipole moments,and transition dipole moments.Finally,electronic configurations and the spin-orbit coupling effects are analyzed and discussed.1.As for the MgS~+system,this paper presents the molecular parameters and spectroscopic constants of the four electronic states correlated with the lowest dissociation limit of the system.To verify the accuracy and reliability of our calculation,the neutral MgS has been calculated with the same method and basis sets that have been used for MgS~+.Our calculation results are in good agreement with the literature data,which indicates the theoretical results of our studies are trustworthy values.The photoelectron spectrum of MgS is simulated,which helps to get insights into the ionization mechanism of MgS~++e?MgS.Hence,our studies provide valuable reference data for subsequent theoretical and experimental studies.2.In our theoretical study for all electronic states of the first four dissociation limit of NaMg,parameters related to the interested states are obtained based on the calculated energy points.Quite a lot crossing and avoid crossings of the PECs are found for NaMg,indicating that the electronic structures of the system are extremely complex and its multi-configuration nature is quite prominent,which further expands our understanding of the system.In addition,the transition properties of the low-lying excited states to the ground state are also studied.The feasibility of the laser cooling scheme of the system is discussed.The result shows that the system is not suitable for the laser cooling scheme.