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.

• 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

• Density Functional Theory (semilocal and hybrid functionals)
• Band Structure Calculations
• Machine Learning (Gaussian Process Regression)
• Ab-initio Thermodynamics
• Charge-Reservoir Electrostatic Sheet Technique (a QM/MM approach)

"Surface Adsorbate Polymorph Prediction with Little Effort - Talk at IPAM, LA, Oct 2017

Video of the talk Surface Adsorbate Polymorph Prediction with Little Effort given at the Optimization and Optimal Control for Complex Energy and Property Landscapes workshop at Los Angles, USA, in Sept 2017.

Video of the talk "Nuts and Bolts of Density Functional Theory", given at the FHI-aims Hands-on Workshop in Berlin, July 2017.

Video abstract for "Doping dependence of the surface phase stability of polar O-terminated (000-1) ZnO", published in The New Journal of Physics, 19 (8), 083012, 2017

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) doi: 10.1063/1.4827017

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) doi: 10.1103/PhysRevLett.111.226802

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

Downloads
The packages below can be downloaded and installed using pip-install packagename

• AIMSTools
• SAMPLE (requires AIMSTools)

Contributor to the FHI aims package

last updated: 04. Jan. 2019