| Reference Label | Details |
|---|---|
| Ruscic anh | B3LYP/6-311++G(3df,3pd) Opt(Z-matrix,VeryTight) Int(UltraFine) Freq(VibRot,Anharmonic,ReadISO) Symm(Loose), or some other DFT |
| est unc | estimated uncertainty |
| Nygren 1992 | M. A. Nygren and L. G. M. Pettersson, Chem. Phys. Lett. 191, 473-476 (1992) The Spectrum and Structure of the C4 Molecule |
| Masso 2006 | H. Massó, M. L. Senent, P. Rosmus, and M. Hochlaf, J. Chem. Phys. 124, 234304/1-8 (2006) Electronic Structure Calculations on the C4 Cluster |