GLOBAL QUANTUM FLUCTUATIONS IN METALLIC PARTICLES

A model of three-dimensional quantum chaotic billiards is used to inve stigate global quantum fluctuations in metallic particles. The quantum system is described by means of a tight-binding Hamiltonian in which the energies of the orbitals at the surface sites are chosen at random in the range (-W/2,W/2). The results indicate that for reasonable val ues of W (on the order of half the bandwidth) the energy fluctuations of the highest occupied level are much larger than the corresponding a verage interlevel spacing. This provides a natural explanation for aut oionization effects in granular metals.