The Role of a Discontinuous Free-Electron Density in Harmonic Generation from Metal Surfaces Topics: Light-matter Interaction; Nonlinear Optics and Photonics; Plasmonic Structures and Quantum dots In Proceedings of the 6th International Conference on Photonics, Optics and Laser Technology PHOTOPTICS - Volume 1, 98-104, 2018 , Funchal, Madeira, Portugal