In pursuit of negative Fukui functions: molecules with very small band gaps

A justification for the likely presence of negative Fukui functions in molecules with small band gaps is given, and a computational study performed to check whether molecules with small band gaps have negative Fukui functions to a chemically significant extent is reported. While regions with negative Fukui functions were observed, significantly negative values for the atom-condensed Fukui functions were not observed.FigureThe silver surface encapsulates the negative regions of the Fukui function, which occur in nodal regions of the HOMO (translucent colored lobes, with different colors for different phases) for this phenalenyl biradical.