DFT-GGA, plane-waves code PWSCF 4, PW91 parameterization for V xc 5 US-PPs 6, wave function cutoff 40 Ryd, charge density cutoff 350 Ryd clean gold surface Au (111) described by repeated supercell slab of 7 Au atomic layers, vacuum region 19.23 Å thick work function is a complex property to calculate ab initio, because it is quite sensitive to computational parameters convergence and to surface structural and electronic details convergence on number of atomic (9) and vacuum (12) layers k-point mesh convergence: 10x10x1 for clean gold 8x8x1 k-points for covered surface. work function is defined as F= V