THEORETICAL-STUDY OF THE ELECTRONIC STATES OF MGC

The singlet, triplet, and quintet states of MgC below about 30000 cm(- 1) are studied theoretically to facilitate spectroscopic studies of th is molecule. The B (3) Sigma(-)-X(3) Sigma(-) band system in the visib le appears to be the best transition to characterize the X(3) Sigma(-) ground state. Our best estimate for the bond length of the X(3) Sigma (-) state of MgC is 2.071 +/- 0.002 Angstrom A, which includes an esti mate of the important core-valence correlation effects using the core polarization potential method. The MgC+ molecule is calculated to have a (4) Sigma(-) ground state and a low-lying (II)-I-2 excited state. T he adiabatic ionization potential of MgC is computed to be 7.74 eV.