Density-functional theory with screened van der Waals interactions applied to atomic and molecular adsorbates on close-packed and non-close-packed surfaces

Abstract

Modeling the adsorption of atoms and molecules on surfaces requires ecient electronic structure methods that are able to capture both covalent and non-covalent interactions in a reliable manner. In order to tackle this problem, we have developed a method within density-functional theory (DFT) to model screened van der Waals interactions (vdW) for atoms and molecules on surfaces (the so-called DFT+vdWsurf method). The relatively high accuracy of the DFT+vdWsurf method in the calculation of both adsorption distances and energies, as well as the high degree of its reliability across wide range of adsorbates, indicates the importance of the collective electronic ects within the extended substrate for the calculation of the vdW energy tail. We examine in detail the theoretical background of the method and assess its performance for adsorption phenomena including the physisorption of Xe on selected close-packed transition metal surfaces and 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) on Au(111). We also address the performance of DFT+vdWsurf in the case of non-close-packed surfaces by studying the adsorption of Xe on Cu(110) and the interfaces formed by the adsorption of a PTCDA monolayer on the Ag(111), Ag(100), and Ag(110) surfaces. We conclude by discussing outstanding challenges in the modeling of vdW interactions for studying atomic and molecular adsorbates on inorganic substrates

First-Principles Models for van der Waals Interactions in Molecules and Materials: Concepts, Theory, and Applications

“…We note that, in popular pairwise vdW corrections, vdW coefficients of molecules on metal surfaces can be overestimated by as much as 500%, because these approaches miss the complex polarization effects in the extended surface that are typically responsible for reducing the vdW coefficients of atoms in metals by 50−500% with respect to the free-atom values. 76,77 The discrepancies in the vdW energy caused by small errors in asymptotic coefficients can lead to qualitatively incorrect conclusions about relative stabilities (not absolute energies) as well, such as when studying molecular crystal polymorphs. 78 In systems of increasing size, the binding arises from an interplay of short-and long-range interactions, so an accurate and reliable vdW method must be able to describe the binding at both equilibrium and asymptotic separations, as well as everything in-between, on equal footing.…”

“…Such renormalized bulk reference parameters can be used to investigate cohesion in solids 80,208 and adsorption of molecules on surfaces. 76,77,101,209 Furthermore, the TS approach was also extended from DFT 60 to the density-functional tight-binding (DFTB) method, 210 as well as classical force fields. 211,212 Sato and Nakai developed an atomic pairwise method that can be considered a direct bridge to the class of nonlocal functionals, by directly expanding an ALL-like density functional into a multipole series around the atomic centers.…”

Tuning the work function of stepped metal surfaces by adsorption of organic molecules

“…The studies above included the vdW force in the calculations, but neglected the pronounced contributions of many-body electronic correlations, which arise from the collective electronic fluctuations in the combined molecule/ surface system [25]. The vdW interactions have been shown to strongly affect the stability and structure of hybrid systems [26][27][28][29][30]. However, the most widely employed vdW-inclusive methods simply add a correction to the density-functional theory (DFT) total energy in the form of a non-local interaction energy [31,32].…”

The role of the van der Waals interactions in the adsorption of anthracene and pentacene on the Ag(111) surface

“…While the first works with an additive pairwise potential, albeit with density-dependent coefficient, the second approach is able to take cooperative effects into account. Both the vdW surf and MBD methods have been shown to provide reliable adsorption energy and height for interfaces between organic molecules (such as benzene and PTCDA) and coinage metal surfaces [22][23][24] . Our results show that the inclusion of vdW corrections is crucial to correctly describe the flat adsorption geometry of anthracene on Ag(111); calculations using "pure" generalized gradient approximation (GGA), without including vdW corrections, resulted in a tilted configuration for anthracene/Ag(111), while the use of the vdW surf approach yielded flat molecular orientation, consistent with experimental observations.…”