Ab initio Study of the Potential Curves for CO (X1Σ+), CH (X2Π) and OH (X2Π)

Calculations on spectroscopic properties of the diatomic systems CO, CH, and OH have been carried out by the multiconfiguration SCF, single reference and multireference single and double excitation CI, and average coupled pair functional methods. An evaluation of the different theoretical approaches is performed in order to get better insight into the selection of appropriate procedures for the calculation of the potential energy surface of the H + CO system.