Theoretical study of Ne-Ne collisions

The molecular framework of Ne-Ne collisional excitation processes in the moderate energy range is reported. Diabatic-like orbitals, fulfilling the diabatic correlations of Lichten (1967) are calculated in two different approximations termed frozen-orbital and rotated-orbital methods. The coupling terms and potential energies computed in both approximations show that the excitation mechanism proposed by Brenot et al. (1975) is not consistent with the experimental findings. Quantal differential cross section calculations performed in the frozen-orbital and in the rotated-orbital approximations show the consistency of these two diabatic approaches. These calculations also show that the excitation processes are primarily induced at the crossings between the promoted 4f sigma u molecular orbital and empty Rydberg sigma u molecular orbitals. The investigation of secondary mechanisms following the sigma u sigma u primary transitions demonstrates that the one- and two-electron processes favour the Ne(2p 5 3p) levels.