At PBE0 level (Figure ), we first observe a slight blueshift followed by an intensity decrease of the silver plasmon band while going from Ag 120 to Ag 100 Au 20 (3.93 and 3.97 eV, respectively). By increasing the gold/silver ratio (Ag 20 Au 100 ), the intensity of the silver plasmon band decreases again and is this time slightly redshifted by 0.03 eV (3.94 eV).