Accurate $\mathit{\text{ab}}\mathit{\text{initio}}$ calculations of RaF electronic structure indicate the need for more laser-spectroscopical measurements

Recently a breakthrough has been achieved in laser-spectroscopic studies of short-lived radioactive compounds with the first measurements of the radium monofluoride molecule (RaF) UV/vis spectra. We report results from high accuracy \emph{ab initio} calculations of the RaF electronic structure for ground and low-lying excited electronic states. Two different methods agree excellently with experimental excitation energies from the electronic ground state to the ${}^2{\mathrm{\Pi }}_{1\mathrm{/}2}$ and ${}^2{\mathrm{\Pi }}_{3\mathrm{/}2}$ states, but lead consistently and unambiguously to deviations from experimental-based adiabatic transition energy estimates for the ${}^2{\mathrm{\Sigma }}_{1\mathrm{/}2}$ excited electronic state and show that more measurements are needed to clarify spectroscopic assignment of the ${}^2\mathrm{\Delta }$ states.