Ab initio study of the electronic structure and optical properties of the Au(111) surface

The present thesis investigates the electronic structure and optical properties of the Au(111) surface through ab initio calculations. The aim of this study is to contribute to the identification of the minimal system for accurate density functional theory simulations of the light-activated adatom formation at gold surfaces. Electronic structure calculations are performed with codes from the Quantum ESPRESSO suite (employing norm-conserving pseudopotentials and the PBE functional), while optical absorption spectra within the random phase approximation are computed using the YAMBO code. After a comprehensive characterization of the electronic structure and optical absorption spectra for bulk gold, Au(111) slabs of thickness varying between 2 and 10 atomic layers are constructed. Their density of states is evaluated, then projected onto the 5d atomic orbitals and layer-resolved. The comparative analysis of the layer-resolved PDOS shows that the central layer of the 5-layer slab begins to approximate the bulk profile; the 5-layer Au(111) slab is thus suggested as minimal model of the gold facet involved in light-induced adatom formation. The optical absorption spectra of the slabs approach the bulk profile above the interband threshold, while thickness-dependent peaks emerge at lower energies.