| C3 | C6 | C8 | Ref. |
|---|---|---|---|
| -18.80 | 1.205[4] | 9.462[6] | M. Marinescu and A. Dalgarno, Phys. Rev. A 52, 311 (1995) |
| -20.13 | 1.612[4] | 1.374[7] | B. Bussery and M. Aubert-Frecon, J. Chem. Phys. 82, 3224 (1985) |
| -18.80 | 1.256[4] | 8.964[6] | F. Vigne-Maeder, Chem. Phys. 85, 139 (1984) |