EXTENDED SSH MODEL FOR C₅₈B₂ AND C₅₈N₂

The extended Su-Schrieffer-Heeger model is used to study the electronic energy levels and molecular structures for two kinds of isomers of C₅₈X₂(X=B, or N). In each case we obtain two sets of stable solutions. For C₅₈X₂ (1, 2), both sets of solutions are found to be reasonable, indicating two different phases. For C₅₈X₂(1, 60 ), only one set of solutions which satisfy the central inversion symmetry is physically reasonable.