"The experimental techniques in the field of Surface Science are under constant upgrade according to the increasing complexity of the systems under study. Experimental developments would benefit from an improvement in their theoretical counterparts. I have wide expertise in the development of theoretical methods for the quantitative structural optimisation of surfaces using Low-Energy Electron Diffraction (LEED). My background also covers the use of Density Functional Theory (DFT) methods applied to the study of atomic structure and physical chemistry in surfaces. In the proposed research, I intend to tackle problems integrating these two areas of expertise. I will describe electron multiple scattering in surfaces under different approximations, making the formalism efficient for nanoscaled adsorbates. On the other hand, typical strategies used in DFT codes often use steepest-descent-based methods to locate total energy minima (equilibrium structures) and saddle points (transition states), which tend to stagnate at local energy minima in the configuration space. I will apply global search methods within DFT, inspired by the electron diffraction techniques I am familiar with, as well as by other areas of knowledge where optimisation techniques are more developed. I will also make use of DFT calculations to study chemical processes on metallic surfaces, focusing in those aimed at the reduction of polluting gas emissions, such as reduction of NOx species. I will attempt a more realistic modelling of the catalytic properties of the surfaces, paying special attention to the effect of defects and surface partial oxidation on the reactivity. An accurate sampling of the configuration space will be key here."