Ground and excited states of group IVA diatomics from localhyphen;spinhyphen;density calculations: Model potentials for Si, Ge, and Sn

摘要

LCGTOhyphen;MPhyphen;LSD results are reported for the spectroscopic constants and electronic structure of the diatomic molecules Si2, Ge2, Sn2, SiGe, SiSn, and GeSn in their lowhyphen;lying electronic states. For the homonuclear molecules we found that the ground state is3Sgr;minus;gwith the most important lowerhyphen;lying excited states being3Pgr;u,1Pgr;u, and1Sgr;+g, respectively. Our results are in good agreement with the available experimental data and also in qualitative agreement with other theoretical studies. We present here the first theoretical study on the heteronuclear molecules, for which experimental data are not available. We found the3Sgr;minus;state to be the lowest, followed by3Pgr; and1Sgr;+states. Model potentials (MP) are reported for the Si, Ge, and Sn atoms. The reliable results for molecules complement those for the atoms and show that the LSD model potentials presented here allow for an accurate description of chemical bonding and spectroscopic properties in the title molecules.