Title: Bond Formation and Reorganization Energy of Adsorbates on Insulating Films: Challenges for Density Functional Theory.
When: Tuesday, May 14, (2019), 12:00.
Place: Sala de Grados, Module 08, Faculty of Sciences, Universidad Autónoma de Madrid.
Speaker: Ivan Scivetti, STFC, Daresbury Laboratory, Sc. Tech., Warrington, UK; Department of Chemistry, University of Liverpool, Liverpool, UK.
Scanning probe experiments of adsorbates on insulating films supported by metallic substrates has led to enormous progress in the imaging, characterization and control of matter at the nano-scale level [1]. Of particular interest is the response of molecular complexes upon the injection of charge [2] and how this excess of energy is released from the geometry distortion [3,4]. Understanding this complex mechanism is crucial in the description of electron transfer [5], a process of vital relevance in many fundamental processes [6].
This talk focuses on the theoretical aspects of these mechanisms via Density Functional Theory (DFT). I shall show that the well-known limitations of standard local and semi-local DFT to describe charge transfer at surfaces can be remedied, in part, if we use the classical perfect conductor approximation for the metal substrate, whereas the insulating film and the adsorbed complex are fully computed within the framework of DFT [7].
As examples of application of this alternative DFT methodology, we shall first consider the bond formation/breaking process in a molecular switch composed of a single gold atom and a perylenetetracarboxylic-dianhydride molecule, and evaluate the interplay between kinetics and electronic repulsion [3]. We will then discuss the redox reaction of naphthalocyanine (NPc) molecules and the challenges to compute the relaxation energy, which has been measured very recently for the first time [4]. Our findings do not only provide unprecedented fundamental insight of the relaxation processes for different molecular charged states, but also demonstrate the relevance of DFT research to support scanning probe experiments.
Following this presentation, only if time allows it, I would like to invite attendees to share their experiences, discuss current challenges, identify common research interests and evaluate future perspectives.
References
- G. Meyer, L. Gross, F. Mohn & J. Repp. CHIMIA, 66, 1, pp. 10-15(6) (2012).
- J. Repp, G. Meyer, S. M. Stojkovic, A. Gourdon & C. Joachim. Phys. Rev. Lett. 94, 026803 (2005).
- F. Mohn, J. Repp, L. Gross, G. Meyer, M. Dyer & M. Persson. Phys. Rev. Lett. 105, 266102 (2010).
- S. Fatayer, B. Schuler, W. Steurer, I. Scivetti, J. Repp, L. Gross, M. Persson, and G. Meyer. Nat. Nanotech. 13, 376-380 (2018).
- Marcus, R. A. Mod. Phys. 65, 599–610 (1993).
- Ratner, M. Nat. Nanotech. 8, 378–381 (2013).
- Scivetti, I. & Persson, M. J. Phys. Condens. Matter 25, 355006 (2013); 26, 135003 (2014); 35, 355002 (2017).
