We have used a recent ab initio CEPA (coupled electron pair approach)
potential energy surface as well as two earlier potential energy surfa
ces to calculate the energies of the lowest rovibronic levels of the n
early degenerate electronic ground states ((2)A' and (2)A'') of the Ar
-NO(X(2) Pi) complex. We use a variational approach which includes the
rotation-vibration, electron angular, and spin momenta coupling but n
eglects nuclear spin coupling. The results allow a direct comparison w
ith measurements of high-resolution rotational spectra in the vibratio
nal ground state. Predictions are also made for the positions of bound
rovibronic levels (J = 1/2), which have not yet been observed.