Benzene and Its Derivatives Adsorbed on Metal Surfaces: A Bag Full of Surprises

The study of molecule/metal interfaces is important for fundamental and applied surface science, and the electronic properties of these interfaces can be tuned by controlling their geometries. In this regard, a particular challenge for electronic structure theory is to reliably model the structure and stability of such hybrid interfaces. Here, we demonstrate that our DFT+vdW$\rm^ {surf}$ method [1] is able to describe 25 systems [\textit{e.g.}, benzene on Au(111) and Pt(111), thiophene/Ag(111), and DIP/Ag(111)] with an accuracy of 0.1~{\AA} in adsorption heights and 0.1~eV in binding energies wrt. reliable experimental data. In addition, our DFT+vdW$\rm ^ {surf}$ calculations lead to a few peculiar findings: (1) The vdW energy can contribute more to the binding of covalently bonded systems than it does in physisorbed interfaces [2,3]; (2) the binding energies of similar molecules can be identical, despite significantly different adsorption heights; (3) the physically bound (precursor) state for aromatics on Pt(111) can be prominently stabilized and long-lived, making it potentially useful in molecular switches [4]. [1] Ruiz, \textit{et al.}, PRL (2012). [2] Liu, \textit{et al.}, PRB (2012). [3] Liu, \textit{et al.}, NJP (2013). [4] Liu, \textit{et al.}, Nat. Commun. (2013).