Abstract
In recent years, evaluating the effect of van der Waals (vdW) forces for many physical systems, including the adsorption of small organic molecules on metal surfaces, became possible thanks to the continuous improvements in vdW density functional theory (DFT). In this work, employing the vdW-DF (revPBE-vdW), the optimized vdW-DF (optB88-vdW, optPBE-vdW, optB86b-vdW), and vdW-DF2 (rPW86-vdW2) methods, we study the adsorption of benzene on a range of (110) transition metal surfaces. We evaluate the performance of the vdW functionals by examining the equilibrium adsorption geometries and energies and comparing the results with the available experimental data and the PBE calculations. Our results show that the optimized vdW-DF functionals predict the equilibrium geometries in good quantitative agreement with some of the available experimental reports. We show the crucial importance of the vdW interactions for accurate description of equilibrium geometries and energies of benzene on transition metal (110) surfaces on which the nature of adsorption varies.