| C3 | C6 | C8 | Ref. |
|---|---|---|---|
| -8.445(0.014) | n/a | n/a | H. Wang, X. T. Wang, C. J. Williams, P. L. Gould, and W. C. Stwalley, Phys. Rev. A 55, R1569 (1997) |
| -8.665 | 6.291[3] | 7.623[5] | M. Marinescu and A. Dalgarno, Phys. Rev. A 52, 311 (1995) |
| -9.340 | 6.868[3] | 5.814[5] | B. Bussery and M. Aubert-Frecon, J. Chem. Phys. 82, 3224 (1985) |
| -8.768 | 6.465[3] | 7.132[5] | F. Vigne-Maeder, Chem. Phys. 85, 139 (1984) |