Ab initio study of the molecular vibrations and electronic structure of the X, B, D and F2Σ+ states of AlO

Molecular vibrations and electronic structure of the X2Σ+, B2Σ+, D2Σ+, and F2Σ+ states of AlO are studied by carrying out ab initio configuration interaction calculations and molecular vibration calculations using accurate potential energy functions. An avoided crossing between the D2Σ+ and F2Σ+ potential energy curves occurs in the neighborhood of 4.0 a0 and results in irregular vibrational levels of the D and F2Σ+ states. The vibrational constants for the F2Σ+ state are predicted from the vibrational levels not involved in the irregularity. Configuration mixing is important in describing the B, D, and F2Σ+ states. The F2Σ+ state at and around its well minimum and the D and F2Σ+ states in the avoided crossing region are characterized in terms of their main configurations and dipole moment functions.