Under its strong π-bond conjugation, the oscillations for the cumulenic structure are approximately two times larger amplitudewise (σ0) as compared to those obtained for the polyyne molecule. This difference can be explained by the metallicity of long-chain cumulenes and semi-conductivity of long-chain polyynes , resulting in different band gaps, here understood as HOMO-LUMO gap. For metals, the band gap between the conductive band and the valence band is zero, causing a much higher free charge carrier density than for semiconductors with wider band gaps. This results in metallic conductivity being much larger than for semiconductors.