Relativistic calculations of potential energies of low-lying electronic states and transition dipole moments of the OH radical

Relativistic calculation of molecular properties of low-lying electronic states of the OH radical has been performed using various non-empirical methods of quantum chemistry. As a result of the study, potential energy curves for electronic states in a wide range of internuclear distances converging to the three lowest dissociation limits of the OH radical have been obtained. The dependencies of relativistic corrections, Gaunt contribution, spin-orbit splitting and quantum-electrodynamic correction to the total energy on the internuclear distance have been established for the ground state. Additionally, the dipole moment curve of the ground state was calculated over a wide range of internuclear distances. For electronic states asymptotically approaching the first dissociation limit, the transition dipole moment curves for transitions to the ground state, including spin-forbidden ones, have been calculated. The results obtained are important for investigating the processes of hydroxyl molecule formation in the interstellar medium.