Investigating Complex Surface Phenomena Using Density Functional Theory

Surfaces of some materials exhibit vastly different structure than the bulk-truncated atomic structure due to the reduced surface atomic coordination that leads to surface dangling bonds and/or surface stress. In order to relieve the stress, partial dislocation networks are formed on some surfaces, changing the surface periodicity to tens or hundreds of nanometers. By using Pt(111) and Ag/Ag/Pt(111) surface reconstructions as examples, we demonstrate how such large length scale pattern formation can be investigated using “classical” models parameterized within density functional theory. We then present an example of determining the magnetic state of ultrathin films on semimetallic substrates. It is possible that such magnetic films also get reconstructed due to the mismatch in lattice spacing between the film and the substrate. Although the pattern formation on magnetic films can be studied using similar type of models, determining the magnetic state of such superstructures requires further modeling efforts