First-principles calculation of structural stability of alkali-atom adsorbed metal surfaces

Structural stability of alkali-atom adsorbed metal surface systems, Al(0 0 1)–Na and Al(0 0 1)–Li at coverages of 1/2 and 1/4, is studied in terms of a first-principles plane-wave pseudo-potential approach within the local density approximation. Optimized structural parameters and adsorption energies calculated at the 1/2 coverage are quite consistent with our previous all-electron approach. Mechanism of the structural stability is discussed by comparing the optimized structure and adsorption energies at the different coverages of 1/2 and 1/4.