Determination of contracted atomic basis sets for the study of CN; application to the MCSCF calculations of its spectroscopic constants

Contracted atomic basis sets have been constructed from ANOs in order to describe the ground and excited states of C and N and their anions. Application is given with the MCSCF calculation of the vibration frequency of CN⁻ and of other spectroscopic constants. A procedure is proposed to do MCSCF calculations when some problems of convergence arise.