NONMETAL-METAL TRANSITION IN NI CLUSTERS

We have studied the nonmetal-metal transition in Ni clusters. A self-c onsistent tight-binding method for the s, p and d valence electrons ha s been used to calculate the density of states and the prescription em ployed to identify the nonmetal-metal transition was Kubo's criterion that the density of states at the Fermi level should exceed 1/k(B)T. T he calculated critical cluster size decreases fast with increasing tem perature T and at the liquid nitrogen temperature clusters of about 50 atoms already present metallic behavior. (C) 1997 Elsevier Science Lt d.