Herein, chemical adsorption properties of the thiol-functionalized metallocene molecules [M(C5H4SH)(2)] on Si(111)-Ag root 3 x root 3 surface were investigated using density functional theory calculation. For this purpose, thiol-modified ferrocene [Fe(C5H4SH)(2)], osmocene [Os(C5H4SH)(2)], and ruthenocene [Ru(C5H4SH)(2)] molecules were attached on the surface via two different binding models. The more favorable chemical binding energies of [Fe(C5H4SH)(2)], [Os(C5H4SH)(2)], and [Ru(C5H4SH)(2)] molecules were calculated as 23.42, 22.15, and 22.00 eV, respectively. The results showed that the adsorption energies of metallocene molecules change independently by increasing the radius of metal ions where on going down the group of the periodic table. The calculated adsorption energies showed that [Fe(C5H4SH)(2)] molecule was more stable on the Si(111)-Ag root 3 x root 3 surface. By calculating the electronic band structure for metallocene/Si(111)-Ag root 3 x root 3 surfaces, we identified a flat dispersion band in a part of the surface Brillouin zone. (C) 2015 Wiley Periodicals, Inc.