Use of regions of space defined by topological analysis of electron localization function (ELF) as reactivity descriptors is explored. By starting from the fact that the ELF presents high values in the regions where it is most probable to find an electron pair and that the square of the HOMO is a good measure of the reactivity of a molecule, it is proposed that the integration of the square of the HOMO over the volumes defined by the ELF should be a local index for predicting the most nucleophilic site of a molecule. We present here some computational results on simple systems in order to get some insights about this possibility.
