DUGi

The linear response kernel of conceptual DFT as a measure of aromaticity

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We continue a series of papers in which the chemical importance of the linear response kernel chi(r, r’) of conceptual DFT is investigated. In previous contributions (J. Chem. Theory Comput. 2010, 6, 3671; J. Phys. Chem. Lett. 2010, 1, 1228; Chem. Phys. Lett. 2010, 498, 192), two computational methodologies were presented and it was observed that the linear response kernel could serve as a measure of electron delocalisation, discerning inductive, resonance and hyperconjugation effects. This study takes the analysis one step further, linking the linear response kernel to the concept of aromaticity. Based on a detailed analysis of a series of organic and inorganic (poly) cyclic molecules, we show that the atom-condensed linear response kernel discriminates between aromatic and non-aromatic systems. Moreover, a new quantitative measure of aromaticity, termed the para linear response (PLR) index, is introduced. Its definition was inspired by the recent work published around the para delocalisation index (PDI). Both indices are shown to correlate very well, which emphasises the linear response kernel’s value in the theoretical description of aromaticity

The authors thank Jens Top for performing preliminary calculations. N. S. acknowledges the Research Foundation-Flanders (FWO) for a position as research assistant. F. D. P. and P. G. thank the FWO and the Vrije Universiteit Brussel for continuous financial support. M. S. thanks the Spanish MICINN (CTQ2008-03077/BQU and CTQ2011-23156 projects) and the Catalan DIUE (2009SGR637 and ICREA Academia 2009 prize)

Royal Society of Chemistry (RSC)