Molecular shape, capacitance, and chemical hardness

摘要

To elucidate the effects of overall molecular shape upon the electronic response properties of molecules and nanoclusters we recently have considered various jellium duster models for the mean excitation energy. Here we apply similar models to characterize the relationship among gross molecular shape, the capacitance of an identically shaped spheroidal conductor, and the chemical hardness of the system eta = (I - A)/2 (I, A are the first ionization energy and electron affinity, respectively). As with the mean excitation energies, the models possess reasonable predictive capability for these cases. Within a strict density functional interpretation we also show that, quite unlike a classical capacitor, the capacitance of a nanoscale object is not independent of the way charge is added. Classical behavior is recovered by an average over the final charge state of the nanoscale capacitor. (C) 2000 John Wiley & Sons, Inc. [References: 29]