POINT-ION APPROXIMATION WITHIN THE MARCH MODEL FOR THE FULLERENE MOLECULE

We present an approach of the March model [N. H. March, Proc. Cambridg e Philos. Sec. 48, 665 (1952)] for the fullerene molecule by employing a point-ion approximation. Accordingly, the model with which we shall be concerned is a high-density gas of pi electrons in its ground stat e with a discrete positively charged background disposed in a t - icos ahedral symmetry. The density of pi electrons is derived within the fi rst-order approximation of the perturbation theory and then Poisson's equation is solved analytically by imposing natural limits for the ful lerene molecule. We have found both inside and outside the fullerene c age distinctive peaks for the electron distribution and a larger fract ion of the pi electrons contained inside the molecule. We must stress here that the other results recorded in a continuum positive charge ap proximation of the March model for the fullerene molecule predict that only less than half of all the pi electrons are inside the shell.