Stability of multivacancies in graphene

The stability of graphene multivacancy systems is studied using Density Functional Theory (DFT) calculations. This work describes the evolution of the energy of formation per carbon atom for zigzag and armchair complementary figures -i.e. the figure formed by the carbon atoms extracted from graphene to form the vacancy-. Multivacancy systems formed when armchair complementary figures are removed are more stable for higher orders (>5) in comparison with the zigzag ones. The case of the construction of a 6-order vacancy from a 5-order one (branch-like) is discussed with the dependence on the place where the extra carbon atom is removed from graphene. The stability of multivacancy systems could be explained through the relative positions of the pentagonal rings present in the resulting defected graphene structure, as the more relevant factor. Other secondary factors that affect the stability of a graphene multivacancy system are the dangling bonds magnetic arrangements and their steric hindrance.