Electronic structure and magnetism ofRhn(n=2–13)clusters

Abstract

Theoretical studies of the ground-state geometries, electronic structure, binding energies, ionization potentials, and magnetic moments of Rh{sub n} (n=2{endash}13) clusters have been carried out using a combination of molecular-dynamics and {ital ab initio} density-functional scheme including gradient corrections. For clusters containing less than eight atoms, the ground states have been determined by starting from several random configurations and minimizing the geometry using first-principles density-functional calculations. For larger clusters, the initial geometries were obtained via molecular-dynamics simulations based on a tight-binding many-body potential and reoptimized using the density-functional approach. The ground-state structures are all compact arrangements and the clusters containing 8, 9, 10, 11, and 12 atoms resemble icosahedral fragments. The clusters are shown to undergo progression of magnetic behaviors with size. While most clusters are ferromagnetic with varying magnetic moments, Rh{sub 4} and Rh{sub 6} are found to have nonmagnetic states that are nearly degenerate with ferromagnetic states. The variation in the magnetic moments is shown to be intimately linked to the electronic structure. {copyright} {ital 1999} {ital The American Physical Society}