Structure and Stability of C20H3 Radical

Density functional theory B3LYP with 6‐31G?? basis set has been used to investigate the geometries, rotational constants, dipole moments, energy gaps and vibrational frequencies of nine series of isomers of C₂₀H₃ radical. The result shows that the bowl‐like structure with C₁ symmetry is the most stable structure, in which the three hydrogen atoms locate on the edge carbon atoms, and the two hydrogen atoms are neighbouring and the other one has a two‐ carbon atom interval to the neighbouring hydrogen. In addition, the relationship between the energy and the position of one hydrogen atom from end to middle on the linear structures of C₂₀H₃ radical with two hydrogens atoms located on two ends was obtained, which shows the energy increase monotonously. Furthermore, hydrogenation can relax the strain and make the isomer of C₂₀ more stable.