Reactivity Indices in Density Functional Theory:  A New Evaluation of the Condensed Fukui Function by Numerical Integration

The condensed Fukui functions fk of maleimide (1H-pyrrole-2,5-dione) have been calculated using a numerical integration scheme implemented in the deMon program package. The condensed functions show that soft nucleophiles interact with the α carbon atoms, whereas hard nucleophiles interact with the carbonyl carbon atoms, in accordance with the experimental evidence. The present method yields extremely few dispersed values of fk, whatever the basis sets, the numerical grids, and the exchange-correlation functionals used. Finally, the validity of the method has been successfully tested on a set of organic and organometallic molecules.