The conjugated π-orbital system in polyynes results in a set of carbon pairs with triple bonds -formed with orthogonal px and py orbitals of both atoms -separated by single bonds. On the other hand, the double bonds in cumulenes are constructed via alternating px and py orbitals. In both cases, such similar πconjugated orbitals result in the similarity of both averaged EDR profiles (Fig. ). However, EDR shows that electrons delocalize slightly more in cumulene over large distances than in polyyne. Owing the success of free-electron gas approximation in describing FOs in both systems, it is not surprising that EDR profile for the 3D free electron gas has very similar shape as the EDRs for actual molecules (see Fig. ).