Comparison of the previous model of Hébrard et al. (2012) (blue solid lines) with the present work (red solid lines) for the carbon trimer C₃, 2-cyclopropyn-1-yl c-C₃H and 2-propynylidyne l-C₃H, cyclopropenylidene c-C₃H₂, propadienylidene l-C₃H₂ and propynylidene t-C₃H₂, propargyl radical C₃H₃ and allyl radical C₃H₅.