The role of adatoms for the adsorption of F4TCNQ on Au(111)

TL;DR

This study uses advanced computational methods to understand how native adatoms influence the structure and energetics of F4TCNQ molecules adsorbed on gold surfaces, revealing mechanisms of adatom incorporation.

Contribution

It provides new insights into the electronic and energetic factors driving adatom incorporation in molecular adlayers on metal surfaces.

Findings

Adatoms modify adsorption geometry and energy.

Charge transfer influences adatom incorporation.

Electronic structure explains adatom effects.

Abstract

Organic adlayers on inorganic substrates often contain adatoms, which can be incorporated within the adsorbed molecular species, forming two-dimensional metal-organic frameworks at the substrate surface. The interplay between native adatoms and adsorbed molecules significantly changes various adlayer properties such as the adsorption geometry, the bond strength between the substrate and the adsorbed species, or the work function at the interface. Here we use dispersion-corrected density functional theory to gain insight into the energetics that drive the incorporation of native adatoms within molecular adlayers based on the prototypical, experimentally well-characterized system of F4TCNQ on Au(111). We explain the adatom-induced modifications in the adsorption geometry and the adsorption energy based on the electronic structure and charge transfer at the interface. With this, we provide deeper insight into the general mechanisms causing the incorporation of adatoms within an adlayer made of a strong acceptor molecular species.