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 C-60 molecule in;the framework of t he Heisenberg model. his shown that the 12 500-dimensional Kekule spac e 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 Kekule space. This 5828-dimensional subspace is derived from the main Kekule function, which is formed from spin pairs on hexagon-hexagon b onds only, by simple rotations of the three spin pairs in disjoint set s of hexagonal rings of C-60 in all possible ways. This indicates that the concept of the stability of the aromatic sextet still plays an im portant role even in this nonalternant system. Further, the inclusion of some longer range RVB functions like Dewar-type functions and:funct ions involving Claus structures is investigated, and the effect on the ground-state energy as well as;on the nearest neighbor correlation fu nctions is examined. (C) 1998 American Institute of Physics.