Adsorption of thiophene on the RuS2 (100) and (111) surfaces:: A Laplacian of the electronic charge density study

To study the effect of the surface Ru sulfur coordination number and of the surface S-H and Ru-H species into the thiophene adsorption on RuS2, a topologic study of the Laplacian of the electronic density of selected (100) and (111) surfaces was carried out. It was found that a nonbonded local charge concentration on the S atom of the thiophene interacts with a local minimum on the outermost Ru atoms of the surfaces. This interaction is strongly affected by a nonbonded local charge concentration located on the outermost S atoms of the surface. Both interactions combine in such way that the strength of the thiophene adsorption on the unhydrogenated surfaces shows small changes. The main role of the S-H bond is to move away the surface sulfur local charge concentrations from the Ru atoms while the Ru-H species favors the hydride attacks to a local minimum located at the C-alpha of the thiophene molecule.