Density functional calculation of the ionization potentials of small metallic particles

A Density Functional Pseudopotential method is used to compute the ionization potential IP of Sodium, Aluminium and Lead microparticles as a function of particle size. The model particles are formed by a central atom surrounded by successive coordination shells of first neighbours, second neighbours, etc. Maxima in IP are obtained for particles with filled coordination shells. The magnitude of IP correlates with the magnitude of the electron density in the region where the electron is extracted.