The density of states (DOS) refers to the number of electronic states available at a given energy level for electrons in a material, which depends on both the molecule and the surface. The calculated DOS of the adsorptions of Fc/Au(111) are given in Figure . The total density of states (TDOS) of E-Fc/Au(111) and S-Fc/Au(111) in isolation and at adsorption are given in Figure (a) and (b), respectively, whereas the projected density of states (PDOS) contributions from individual elements in E-Fc and S-Fc was conducted, which are given in Figure (c) and (d), respectively.