Variational resonance valence bond study on the ground state of C-60 using the Heisenberg model

A detailed variational resonance valence bond (RVB) study is performed for the S=0 ground state of the C60 molecule in the framework of the Heisenberg model. It is shown that the 12500-dimensional Kekulé space can be divided into two subspaces of respective dimensions 5828 and 6672, of which the first one recovers 99.82% of the energy of the full Kekulé space. This 5828-dimensional subspace is derived from the main Kekulé function, which is formed from spin pairs on hexagon-hexagon bonds only, by simple rotations of the three spin pairs in disjoint sets of hexagonal rings of C60 in all possible ways. This indicates that the concept of the stability of the aromatic sextet still plays an important role even in this nonalternant system. Further, the inclusion of some longer range RVB functions like Dewar-type functions and functions involving Claus structures is investigated, and the effect on the ground-state energy as well as on the nearest neighbor correlation functions is examined. © 1998 American Institute of Physics.

Variational resonance valence bond study on the ground state of C-60 using the Heisenberg model Academic Article