Abstract:
Adsorption of methanethiol onto the three, high symmetry gold surfaces has been studied at the density functional
level using a linear combination of atomic orbitals approach. In all three cases the bond energy between the thiolate
radical and surface is typical of a covalent bond, and is of the order of 40 kcalmol_1. For the (111) surface the fcc
hollow site is slightly more stable than the bridge site. For the (100) surfaces the four-fold hollow is clearly the most
stable, and for the reconstructed (110) surface the bridge/edge sites either side of the first layer atoms are preferred. The
calculated differences in binding energy between the three surfaces indicate that the thiolate will preferentially bind to
the Au(110) or (100) before (111) surface, by about 10 kcalmol_1. The (110) surface is slightly more favourable than
the (100), although the energy difference is only 3 kcalmol_1. The results suggest the possibility of selectively functionalising
the different facets offered by a gold nanoparticle.
