Ordered phases of Na adsorbed on Pt(111): Experiment and theory - art. no.075406

Using low-energy electron diffraction structural analysis and first-princip les calculations based on the generalized gradient approximation we have in vestigated the (root 3x root3)R30 degrees -Na and (2x2)-Na overlayers on Pt (111). In both phases the Na adatoms occupy hcp hollow sites. The measured and calculated adsorption geometries agree quantitatively. We have also stu died the possibility of substitutional adsorption at the coverage Theta =1/ 4. The results are compared with other alkali adsorption systems, in partic ular K on Pt(111). [S0163-1829(00)00944-9].