AbstractPotential energy functions of the MgH molecule are investigated by the MRCI method using large active space and basis sets. The calculations are performed up to the Mg(3s3d,1D) + H dissociation limit. The molecular constants compare well with the available data. The dipole moment functions exhibit a series of crossings due to the strong interactions between the states. Radial and rotational couplings among these states are also calculated, with a state-averaged MCSCF approach. This work will enable calculations of collisional cross sections and rate coefficients, important for the modelling of stellar spectra when collisions compete with radiative processes in non-LTE conditions.
Highlights•The potential energy functions of the 16 lowest doublet electronic states of the MgH molecule were calculated.•Importance of mutual neutralization Mg+ + H− and ionization from Mg + H was shown.•Rate coefficients permit to model spectral lines in stellar atmospheres.•Astrophysical consequences are presented.