| C3 | C6 | C8 | Ref. |
|---|---|---|---|
| -17.33 | 9.393[3] | 6.712[6] | M. Marinescu and A. Dalgarno, Phys. Rev. A 52, 311 (1995) |
| -18.68 | 1.013[4] | 8.376[4] | B. Bussery and M. Aubert-Frecon, J. Chem. Phys. 82, 3224 (1985) |
| -17.54 | 9.651[3] | 6.439[6] | F. Vigne-Maeder, Chem. Phys. 85, 139 (1984) |