Stability, metastability and spectroscopic constants of electronic states of NH⁻ and CH⁻

Highly correlated <i>ab initio</i> methods were used in order to calculate potential energy curves (PECs) of the bound electronic states of CH⁻ and NH⁻ anions and the long-range parts of their excited states. The spin–orbit interaction between electronic states has been calculated for the cases in which the couplings were assumed to be responsible for perturbations. The spectroscopic constants of bound states were calculated from the PECs and compared with previous theoretical and/or available experimental values. Also, from the ground states of CH/CH⁻ and NH/NH⁻, the adiabatic electron affinities were given and discussed.