U2 center, adsorption, coadsorption and epitaxial growth of Cu, Ag and Au on LiH(0 0 1) surface: DFT calculations

U2 center, adsorption, coadsorption and epitaxial growth of Cu, Ag and Au on LiH(0 0 1) surface have been studied using quantum clusters embedded in a simulated coulomb field that closely approximates the Madelung potential of the host surface and density functional theory calculations with effective core potentials on Ag, Cu and Au. The metal atoms are preferentially adsorbed on the top of the anionic species and the physical adsorption of metal atoms is enhanced by ≈0.0147 hartrees under the effect of U2 center imperfection. No barrier heights were detected for diffusion of metal atoms on the surface. The adsorption energies follow the trend Au>Cu>Ag and are correctly explained in terms of the band structure. In several cases the coadsorption is greater than the adsorption of a single adsorbate and metal atoms grows expitaxially on the surface following the growth mode mechanism: (i) M/H, (ii) M2/LiH, (iii) M3/Li2H, (iv) M4/Li2H2.