Cobalt impurities on noble-metal surfaces

First-principles calculations, based on the local-spin-density approximation, are performed for cobalt atoms deposited on noble-metal surfaces. The local density of states at the cobalt site shows a narrow peak at the Fermi energy, which is of minority spin and d character. The d orbital of m = 0 symmetry, which must be mostly responsible for tunneling conductance from this surface site, makes a substantial contribution at E-f. Due to hybridization the same peak also appears, but reduced, at neighbor atoms. This result can be used for the interpretation of recent cryogenic scanning tunneling microscopy experiments. [S0163-1829(99)02113-X].