English

Cayley sum graphs and eigenvalues of $(3,6)$-fullerenes

Combinatorics 2007-12-12 v2

Abstract

We determine the spectra of cubic plane graphs whose faces have sizes 3 and 6. Such graphs, "(3,6)-fullerenes", have been studied by chemists who are interested in their energy spectra. In particular we prove a conjecture of Fowler, which asserts that all their eigenvalues come in pairs of the form {λ,λ}\{\lambda,-\lambda\} except for the four eigenvalues {3,1,1,1}\{3,-1,-1,-1\}. We exhibit other families of graphs which are "spectrally nearly bipartite" in this sense. Our proof utilizes a geometric representation to recognize the algebraic structure of these graphs, which turn out to be examples of Cayley sum graphs.

Keywords

Cite

@article{arxiv.0712.1631,
  title  = {Cayley sum graphs and eigenvalues of $(3,6)$-fullerenes},
  author = {Matt DeVos and Luis Goddyn and Bojan Mohar and Robert Samal},
  journal= {arXiv preprint arXiv:0712.1631},
  year   = {2007}
}
R2 v1 2026-06-21T09:52:42.128Z