Adsorption and coadsorption of H and Li on Ag(100) surface: DFT studies including dispersion correction

We report on the results of DFT calculations of H, Li adsorption and Li+H coadsorption on Ag(100) surface. By using the GGA–PBE functional and DFT+d3, we obtain the adsorption energies, coadsorption energies, structural parameters, work function change and dipole moments. Our GGA–PBE calculations show that H prefers the bridge site at 0.25 and 0.50 ML coverages but hollow site at 0.75 and 1.00 ML coverages. With the DFT+d3 functional, we find that H is most stable at bridge site at 0.25 ML coverage, however, it prefers the hollow site at 0.50 ML, 0.75 ML and 1.00 ML coverages. For Li adsorption, both GGA–PBE and DFT+d3 functionals show that Li is most stable at hollow site. For Li and H coadsorption, we find that Li at the hollow site with H at the nearest-neighbor bridge site as the most energetically favorable configuration. The evolution of local electronic structures of the adsorbates and Ag(100) surface has been analyzed in terms of local density states. Our calculations show a decrease in the work function when Li and H are coadsorbed on the Ag(100) surface which suggests a possible transfer of electron from the Li-H adsorbates to the Ag(100) surface.