Autoionising states of He₂²⁺: adiabatic potential energy curves

The adiabatic potential energy curves of the He 2 2+ system are obtained by the configuration-interaction method using 33 terms of one-centre Slater-type orbitals as basis functions. The calculation is carried out in the range of internuclear distance. The calculation is carried out in the range of internuclear distance R from 0.0 to 0.5 atomic units. The results include the potential curves of the autoionising states, 1 Sigma g (2s sigma 2 ,2p sigma 2 ,2p pi 2 ), 1 Pi g (2p sigma 2p pi ) and 1 Delta g (2p pi 2 ). Both computations with and without the 1s sigma nl lambda configurations are performed and the results are compared. The potential curves of states 1 Sigma g (2s sigma 2 ) and 1 Sigma g (2p sigma 2 ) have a pseudo-crossing at R approximately=0.2 au.