Polyenes with maximum HOMO-LUMO gap
PW Fowler, P Hansen, G Caporossi, A Soncini
CHEMICAL PHYSICS LETTERS | ELSEVIER SCIENCE BV | Published : 2001
On the basis of a variable neighbourhood search with the AutoGraphiX software, it is conjectured that for even numbers of atoms the fully conjugated acyclic π system of maximum HOMO-LUMO gap is a 'comb' in which each vertex of a backbone carries a single pendant edge. Chemically, this represents CnH3n/2+2, an α,ω-diene with methylene groups attached at all intermediate positions. As n increases without limit, the conjectured asymptotic dimensionless gap is 22-2. Odd-numbered graphs that would have maximum gap as singly charged π systems are reported for up to 41 vertices; they are related to comb graphs. © 2001 Elsevier Science B.V.