AB-INITIO CALCULATIONS ON THE ELECTRONIC STATES OF GAAR AND GAAR+

The 1-2 (2) Pi(1/2), 1-2 (2) Pi(3/2), and 1-3 (2) Sigma(1/2)(+) states of GaAr and the 1 (1) Sigma(+) and 1 (3) Sigma(-) states of GaAr+ are calculated by ab initio methods. Spectroscopic properties for these s tates are compared with experimental data, and the existence of potent ial barrier for the Rydberg (2) Sigma(1/2) states is explained. We hav e also proved the nonbonding character of the 1 (2) Pi(1/2)(X) State o f GaAr. The bond energy of the doubly excited 1 (3) Sigma(-) state, 12 557 cm-l, is much larger than that of the ground state (X (1) Sigma(- )) of GaAr+, 584 cm(-1), which in turn is more strongly bound than the neutral species (70 cm(-1) for the ground state, 340 cm(-1) for the 2 (2) Pi(3/2) state). The nonbonding character of the X (2) Pi(1/2) Sta te of GaAr can be attributed to the spin-orbit interaction. Transition properties between these states are also calculated. (C) 1997 America n Institute of Physics.