Tetragonal strain in MgO thin films supported at the Ag(1Â 0Â 0) surface: A periodic ab initio study

In this work the morphology of MgO ultrathin films of thickness T from 1 to 3 monolayers (ML), supported at the Ag(1 0 0) surface, has been accurately addressed by employing periodic quantum chemical calculations. The condition of perfect epitaxy imposes to the overlayer a strain whose elastic constants are the same as in the bulk. In the case of T = 3 ML, the in plane and the out of plane Mg-O distances and the interface distance are in excellent agreement with the available experimental data.