MINDO/3 study of the interaction of small carbon clusters

Interaction of small carbon clusters is studied using the MINDO/3 method. Energetic barriers for coagulation and isomerization are estimated. It is shown that coagulation of two linear chains leads to formation of a chain with possible closure to a monocyclic ring, while a linear chain and a ring results in a monocyclic ring. The barriers for these processes are less than 0.5 eV for coagulation and 2 eV for isomerization. Coagulation of two rings leads to a bicyclic cluster with a barrier of 0.2–0.7 eV. Binding of two even rings is relatively weak (1.5–2.0 eV). Odd and even rings may form a non-planar bicyclic cluster with an energy gain of 3.0–4.0 eV. Most stable structures result from two odd rings with binding energies of ≈ 5 eV.