Large-scale surface reconstruction energetics of Pt(100) and Au(100) by all-electron density functional theory

The low-index surfaces of Au and Pt all tend to reconstruct, a fact that is of key importance in many nanostructure, catalytic, and electrochemical applications. Remarkably, some significant questions regarding their structural energies remain even today, specifically for the large-scale quasihexagonally reconstructed (100) surfaces: rather dissimilar reconstruction energies for Au and Pt in available experiments and experiment and theory do not match for Pt. We here show by all-electron density functional theory that only large enough "(5XN)" approximant supercells capture the qualitative reconstruction energy trend between Au(100) and Pt(100), in contrast to what is often done in the theoretical literature. Their magnitudes are then in fact similar and closer to the measured value for Pt(100); our calculations achieve excellent agreement with known geometric characteristics and provide direct evidence for the electronic reconstruction driving force.