Adsorption geometry and the interface states: The relaxed and compressed phases of NTCDA/Ag(111)

TL;DR

This study combines experimental two-photon-photoemission measurements with DFT calculations to accurately analyze the interface states of NTCDA monolayers on Ag(111), highlighting the importance of adsorption geometry and electronic structure.

Contribution

It demonstrates the reliability of current theoretical approaches in modeling metal-organic interfaces by comparing experimental data with DFT calculations for different overlayer structures.

Findings

Experimental interface state energies match DFT predictions with various dispersion treatments.

Both relaxed and compressed NTCDA/Ag(111) structures show high agreement between theory and experiment.

The study confirms the accuracy of DFT methods in describing geometric and electronic properties of the interface.

Abstract

The theoretical modelling of metal-organic interfaces represents a formidable challenge, especially in consideration of the delicate balance of various interaction mechanisms and the large size of involved molecular species. In the present study, the energies of interface states, which are known to display a high sensitivity to the adsorption geometry and electronic structure of the deposited molecular species, have been used to test the suitability and reliability of current theoretical approaches. Two well-ordered overlayer structures (relaxed and compressed monolayer) of NTCDA on Ag(111) have been investigated using two-photon-photoemission to derive precise interface state energies for these closely related systems. The experimental values are reproduced by our DFT calculations using different treatments of dispersion interactions (optB88, PBE-D3) and basis set approaches (localized numerical atomic orbitals, plane waves) with remarkable accuracy. This underlines the trustworthiness regarding the description of geometric and electronic properties.