Abstract
Potential energy curves for the low-lying electronic states of the title molecules in their neutral and anionic forms have been calculated by means of the diffusion Monte Carlo method. The effect of different trial functionals has been investigated using single determinants constructed from density functional theory (DFT) orbitals with B3LYP, B3PW91, and M06-2X functions. Bond length, vibrational frequency, and electron affinity have also been numerically derived for the selected species and the ground state has been assigned. Spectroscopic parameters obtained are interpreted and compared to their isovalents, shedding some light on further investigations on the selected dimers.