The mission of the Hofmann group is the computational discovery of novel materials and material combinations from first principles. We focus on thin film and interfaces, that are of technilogical relevance for nanotechnology applications, such as organic solar cells and OLED displays. We focus on organic thin films, which often assume particular polymorphs and exhibit properties superior to that of the bulk.
To achieve this mission, my group and I pursue two complementary avenues. One part applies density functional theory (DFT) to pertinent surface science problems at inorganic/organic interfaces, with the goal to identify and push back the limits of the state-of-the-art methodology. The second part of my group develops the machine-learning algorithm "SAMPLE" to predict the structure and the properties of thin film polymorphs.
We are presently working on three complimentary FWF-funded projects. In "Tuning of the Interaction Strength", the purpose is to choose the substrate on which the thin film are grown, in order to obtain materials with specific, desired properties. The project "Defects in Organic Monolayers" investigates the nature and the impact of defects and disorder on the electronic structure. Finally, the project "MAP-DESIGN" aims to develop recipies, which allow to produce predicted materials also experimentally. This will close the gap between computational material design and its realization in a lab.
Our research interests include
Structure Determination and Prediction
Polymorphism and Metastable Phases
Phase Diagrams and Phase Transformations
Charge and Energy Transfer Across Interfaces
Adsorption Processes of Organic Molecules
Defects in Organic Monolayers
Spontaneous Symmetry Breaking in Adsorbate Layers
Doping and Long-Range Band-Bending in Semiconductors
which we study using:
Density Functional Theory (semilocal and hybrid functionals)
Band Structure Calculations
Machine Learning (Gaussian Process Regression)
Charge-Reservoir Electrostatic Sheet Technique (a QM/MM approach)
(Some) Master and Bachelor projects can be found using the links on the left side of this page. Usually, more are available - inquire within.
Personal data Featured Videos of Recent Talks and Papers
Highlighted publications (open access) O.T. Hofmann, P. Rinke, M. Scheffler, G. Heimel, "Integer versus Fractional Charge Transfer at Metal(/Insulator)/Organic Interfaces: Cu(/NaCl)/TCNE", ACS Nano just accepted, doi: 10.1021/acsnano.5b01164
O.T. Hofmann, V. Atalla, N. Moll, P. Rinke, M. Scheffler, "Interface dipoles of organic molecules on Ag(111) in hybrid density-functional theory", New Journal of Physics, 15, 123028 (2013), doi: 10.1088/1367-2630/15/12/123028
O.T. Hofmann, J.C. Deinert, Y. Xu, P. Rinke, J. Stähler, M. Wolf, M. Scheffler, "Large work function reduction by adsorption of a molecule with a negative electron affinity: Pyridine on ZnO(1010)", Journal of Chemical Physics 139, 174701 (2013)
Y. Xu, O.T. Hofmann, R. Schlesinger, S. Winkler, J. Frisch, J. Niederhausen, A. Vollmer, S. Blumstengel, F. Henneberger, N. Koch, P. Rinke, M. Scheffler, "Space-Charge Transfer in Hybrid Inorganic-Organic Systems", Physical Review Letters 111, 226802 (2013)
A. Tkatchenko, L. Romaner, O.T. Hofmann, E. Zojer, C. Ambrosch-Draxl, M. Scheffler: "van der Waals Interactions Between Organic Adsorbates and at Organic/Inorganic Interfaces", MRS Bulletin 35, 435 (2010). doi: 10.1557/mrs2010.581
O.T. Hofmann, D.A. Egger, E. Zojer, “Work-function modification beyond pinning: When do molecular dipoles count?”, Nano Lett. 10, 4369 (2010). doi: 10.1021/nl101874k
The packages below can be downloaded and installed using pip-install packagename