LDA THEORY OF THE COVERAGE DEPENDENCE OF THE LOCAL-DENSITY OF STATES - LI ADSORBED ON RU(001)

To understand recent P-decay NMR experiments on Li atoms chemisorbed o n a Ru(001) surface, the work-function changes and the local density o f states (LDOS) at E-F and at the Li nucleus are determined from first -principles local-density full potential linearized augmented plane wa ve calculations for three coverages (Theta =1, 0.25, and 0.11) and two possible sites for Li (fcc and hcp). From full structure optimization s by means of total energy and atomic force calculations, both a surfa ce and in-plane relaxation are found, and Li chemisorption site prefer ences are determined as a function of coverage. The calculated LDOS is constant for low coverage whereas the work function changes substanti ally-both in very good agreement with the P-decay NMR experiments. In contrast, the LDOS at high coverage is predicted to increase by a fact or of 2.