The calculations of the energies of the singlet doubly excited states 2p 2 1 D, 3d 2 1 G, 4f 2 1 I of helium-like systems we have done in our previous paper [Biaye et al., Eur. Phys. J. D 13, 21 (2001).] are extended to the other singlet doubly excited (nl) 2 states with n ≤ 4. The energies are calculated in the framwork of the variation method by using some special forms of Hylleraasa-type wave functions with a real Hamiltonian. The results which we have obtained are in good agreement with some experimental data and other theoretical results.

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The potential energy surface is computed at the explicitly correlated coupled cluster with simple, second and perturbative triple excitation method (CCSD(T)-F12) in connection with the augmented-correlation consistent-polarized valence triple zeta (aug-cc-pVTZ) Gaussian basis set for the NeH + −He system. The calculations were performed by first taking into account the vibration of the molecule and then averaging the so-obtained three-dimensional potential. From this average interaction potential, cross-sections among the 11 first rotational levels of NeH + induced by collision with He are calculated for energies up to 4000 cm −1 using the quantum mechanical close coupling (CC) approach. Collisional rate coefficients are obtained by thermally averaging these cross-sections at low temperature (T ≤ 300 K). The propensity rules of the rotational transitions obtained in this paper are discussed and compared with those of HeH + and ArH + in collision with electron. This work may be helpful for the eventual investigations, both theoretical and experimental, focused to detect the key cationic noble gas hydride NeH + in the interstellar and circumstellar media as well as in laboratory experiments.

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