Topological Stone–Wales Defects Enhance Bonding and Electronic Coupling at the Graphene/Metal Interface

B. P. Klein, A. Ihle, S. R. Kachel, L. Ruppenthal, S. J. Hall, L. Sattler, S. M. Weber, J. Herritsch, A. Jaegermann, D. Ebeling, R. J. Maurer, G. Hilt, R. Tonner-Zech, A. Schirmeisen, J. M. Gottfried, ACS Nano 16, 11979-11987 (2022)

"Defects in Graphene subtly affect the structural and electronic properties. We perform a detailed joint experiment/theory investigation of molecular precursors of pristine graphene and Stone-Wales defects in graphene to assess the structural and spectroscopic changes imposed by defects."

The Nuts and Bolts of Ab-Initio Core-Hole Simulations for K-shell X-Ray Photoemission and Absorption Spectra

B. Klein, S. J. Hall, R. J. Maurer, J. Phys. Condens. Matter 33, 154005 (2020)

"We present the numerical and technical details of our variants of the DeltaSCF and transition potential method (coined DeltaIP-TP) to simulate XPS and NEXAFS transitions. Using exemplary molecules in gas-phase, in bulk crystals, and at metal-organic interfaces, we systematically assess how practical simulation choices affect the stability and accuracy of simulations. We particularly focus on the choice of aperiodic or periodic description of systems and how spurious charge effects in periodic calculations affect the simulation outcomes. For the benefit of practitioners in the field, we discuss sensible default choices, limitations of the methods, and future prospects."

Enhanced Bonding of Pentagon–Heptagon Defects in Graphene to Metal Surfaces: Insights from the Adsorption of Azulene and Naphthalene to Pt(111)

Benedikt P. Klein, S. Elizabeth Harman, Lukas Ruppenthal, Griffin M. Ruehl, Samuel J. Hall, Spencer J. Carey, Jan Herritsch, Martin Schmid, Reinhard J. Maurer, Ralf Tonner, Charles T. Campbell, and J. Michael Gottfried, Chem. Mater. 32, 1041-1053 (2020)

"We show here that the interface properties may be controlled by topological defects, such as the pentagon–heptagon (5–7) pairs, because of their strongly enhanced bonding to the metal. To measure the bond energy and other key properties not accessible for the embedded defects, we use azulene as a molecular model for the 5–7 defect. Comparison to its isomer naphthalene, which represents the regular graphene structure, reveals that azulene interacts more strongly with a Pt(111) surface. Using a combination of single-crystal adsorption calorimetry, x-ray photoelectron and photoabsorption spectroscopies (XPS/NEXAFS), and Density Functional Theory, we fully characterize the adsorption strength, the surface structure and surface chemistry of 5-7 defect systems on Pt(111). Our model study shows that the topology of the π-electron system strongly affects its bonding to a transition metal and thus can be utilized to tailor interface properties."

Computational design of metal-supported molecular switches: Transient ion formation during light- and electron-induced isomerisation of azobenzene

R. J. Maurer and K. Reuter, J. Phys. Condens Matter, DOI:10.1088/1361-648X/aaf0e1 (2018), Invited Article

"Using DFT and linear expansion Delta-Self-Consistent DFT excited-state calculations, we systematically analyse important design parameters that define successful light-induced molecular switching of azobenzene."

Excited-state potential-energy surfaces of metal-adsorbed organic molecules from linear expansion Δ-self-consistent field density-functional theory (ΔSCF-DFT)

R. J. Maurer, K. Reuter, J. Chem. Phys. 139, 014708 (2013)

We implement and test a method to efficiently calculate excited states of organic molecules on metal surfaces.