Knowledge Bank

Calculations are reported on the spectroscopy of lithium boride (LiB) in support of experimental efforts in the High Energy Density Matter (HEDM) program at the Air Force's Phillips Laboratory. Internally contracted multireference configuration-interaction calculations employing extended one-particle basis sets and state-averaged complete-active-space self-consistent-field wave functions are carried out for the electronic states dissociating to separated-atom limits below about $30000cm-1$, where the zero of energy refers to the ground-state atoms $(Li\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}S+B\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}P)$. Included in this energy range are states dissociating to $Li(2p)2S+B\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}P,Li(3s)\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}S+B\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}P$, and $Li(2s)\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}S+B(2p2)\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}P$. The $X3\Pi$ state of the molecule, with $De=9872cm-1$ and $re=4.06a0$, is lower in energy than the $(1)\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Sigma +$ state $(De=7940cm-1$ and $re=4.52a0)$ by $1932cm-1$. Also dissociating to ground-state atoms, the $(1)\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}\Pi$ state exhibits a significant minimum, with $De=3627cm-1$ and $re=4.17a0$. Potential-energy curves, transition moments, and spectroscopic constants are reported for the upper and lower states involved in transitions that might be particularly relevant to observing LiB in emission spectra from a corona-excited supersonic expansion.