Prof. Dr. rer. nat. Karsten Reuter

Telefon

+49 89 289-13616

Raum

5403.05.311K

E-Mail

karsten.reuter@ch.tum.de

Links

Homepage
Visitenkarte in TUMonline

Arbeitsgruppe

Theoretische Chemie (Fakultät für Chemie)

Funktionen

• Professor mit Zweitmitgliedschaft am Physik-Department
• Lehrstuhl für Theoretische Chemie (Fakultät für Chemie)

Sprechstunde

nach Vereinbarung

Lehrveranstaltungen und Termine

Ausgeschriebene Angebote für Abschlussarbeiten

Batteriematerialien: LTO für LIBs

Rechargeable lithium-ion batteries (LIBs) are key components of today's technology that power a range of devices from mobile phones to electric vehicles. During the discharge/charge cycles the electrode materials of a LIB take up or release Li ions and electrons, thereby undergoing changes in chemical composition, structure and electronic structure. In case of lithium-transition metal-oxides, which represent an important class of LIB electrode materials, reversible (de)intercalation of lithium ions in their structures can take place, and the redox-reaction involves a change in the oxidation state of the transition metal atoms. The focus of our project is on lithium-titanium-oxide materials, especially on Li4Ti5O12 (LTO), which can be used as an anode material for LIBs. The computational studies aim to contribute to a better atomic scale understanding of materials properties, such as Li ion mobility and electronic conductivity. Key issues to be dealt with include structural disorder and the occurrence of different oxidation states of the titanium atoms as the Li content is varied. In the BSc project you will use density functional theory techniques to study relations between the chemical composition, structural features and the electronic structure of Li-Ti-O materials. Prior experience with Linux and a scripting language is advantageous but not a prerequisite.

geeignet als

• Bachelorarbeit Physik

Themensteller(in): Karsten Reuter

Germanium Interkalation von Graphene auf Siliziumkarbid: Verstehen wir die Grenzfläche?

Germanium intercalated quasi-freestanding monolayer graphene (Ge-QFMLG) grown on SiC has recently been proven to be an ideal material to form ballistic graphene pn-junctions because the graphene layer doping level depends on the Ge layer thickness intercalated between the SiC substrate and the graphene sheet. The p-type doped interface contains double as many intercalated Ge atoms than the n-doped structure. So far all attempts to identify the interface structure were based on density-functional theory (DFT) using smaller approximated unit cells (3 SiC cells). However, for a reliable structure prediction of the two different interfaces the large (6sqrt3x6sqrt3)R30 unit cell (108 SiC and 169 graphene unit cells) is necessary. To correctly address the van der Waals (vdW) bonded graphene layer state-of-the-art dispersion corrections have to be included. A structure search on the bases of DFT for structure sizes with hundreds of atoms is currently computationally too demanding. A promising compromise between computational cost and accuracy is the Density Functional based Tight Binding (DFTB) method incorporating a state-of-the-art vdW correction scheme.

The proposed MSc thesis is part of a collaborative research project with the group of Prof. Dr. F. S. Tautz (Forschungszentrum Juelich). We will perform a multilevel structure search to address the challenges of predicting an interface structure for very large systems. First, under consideration of the substrate symmetry, we will generate trial interface structures. Then, for these structures, we will construct a surface phase diagram using the semi-empiric DFTB method including dispersion corrections to identify the most promising candiates. The search will then be refined by recalculating the lowest energy structure candidates in DFT. In the process, the MSc student will deepen his/her theoretical background in the interdisciplinary field of materials science and become familiar with state-of-the-art computational methods and modeling techniques. Existing knowledge on UNIX based operating systems and basic programming skills (preferably in Python) is desirable.

geeignet als

• Masterarbeit Physik der kondensierten Materie
• Masterarbeit Applied and Engineering Physics

Themensteller(in): Karsten Reuter

Kinetische Monte Carlo Untersuchung der Synthese höherer Alkohole auf Metallkatalysatoren

Higher alcohols are attractive fuel additives since they can be blended directly into gasoline. At present, the sustainable production of ethanol from biomass occurs primarily via fermentation. The synthesis of higher alcohols from biomass-derived syngas (mainly CO and H2) represents an interesting alternative, since it allows for the use of a wider range of biomass sources. Still, the lack of efficient catalysts limits the industrial use of this approach.

The focus of the present project is on the catalytic properties of extended metal surfaces for ethanol synthesis. Experimentally, Rh catalysts show some selectivity and activity towards higher alcohol synthesis, though often in modified forms. With the use of computational modeling we aim for an improved understanding of the reaction mechanism on this type of catalysts. In the proposed B.Sc. project, the student will use density functional theory (DFT) to investigate key reaction steps such as C-C coupling steps on different metal surfaces and at different active sites. Also the effect of the local environment in terms of adsorbate-adsorbate interactions will be investigated. The obtained DFT calculations will be used to establish energetic trends in the form of scaling relations and in the end provide the input for microkinetic models such as mean-field and kinetic Monte Carlo simulations. Prior experience with UNIX based operating systems and a scripting language (e.g. Python) is advantageous, but not a prerequisite.

geeignet als

• Bachelorarbeit Physik

Themensteller(in): Karsten Reuter

Photokatalytische CO2 Reduktion

Among other things humanity is facing two problems in the not too far future, global warming due to an overabundance of greenhouse gasses such as CO2 in the atmosphere and the need to transition away from finite fossil fuels to renewable energies. A way to tackle both these problems presents itself in the form of photochemical carbon dioxide reduction, where sunlight is harnessed to convert CO2 to higher energy products such as methanol. Unfortunately, currently available CO2 photo-reduction catalysts all suffer from very low turnover rates and are therefore not suitable for large scale industrial application. In the proposed Bachelor's project, candidates will employ state of the art computational---such as embedded density functional theory/classical mechanics simulations---and theoretical methods developed in the Reuter group to identify efficiency limiting steps and search for more effective photo-catalysts. Existing knowledge of UNIX based operating systems and programming is desirable, but not a necessity.

geeignet als

• Bachelorarbeit Physik

Themensteller(in): Karsten Reuter

Zeitliche Beschleunigung von kinetischen Monte Carlo Simulationen

The kinetic Monte Carlo (kMC) method is widely used in materials modeling for studying phenomena ranging from transport and chemical catalysis to crystal growth and phase transitions. All of these systems share the common feature that stochastic or non-linear behavior prohibits the system from being modeled using traditional deterministic methods.

The potential accuracy and detailed level of information available from kMC simulations come at the cost of a substantial computational burden associated with the sequential execution of elementary processes such as adsorption, desorption, diffusion and reaction. The computational cost of kMC simulations typically grows rapidly with an increasing disparity in timescales between two or more processes. For example, surface diffusion processes, representing a hop between two lattice sites, typically occur with rate constants many orders of magnitude higher than those of surface reactions. As a consequence, computational resources are potentially wasted in the repeated execution of fast diffusion processes, preventing an efficient simulation of the macroscopic evolution of the system.

The main tool to be used for this project is the 'kmos' kMC framework; an extensible, modular software package, actively developed and used in our group. Recently, an extension has been implemented to deal with timescale disparity problems and achieve a temporal acceleration of kMC simulations. The interested student will be expected to familiarize him or herself with the concept of kMC simulations and with the `kmos' package and to implement and run a collection of kMC models of varying levels of complexity. The models used will include some developed in the Reuter group and some obtained from the scientific literature. The performance data obtained will be used to identify bottlenecks and guide the further development of `kmos'. Basic knowledge of UNIX based operating systems and some experience with programming (and/or scripting) languages (preferably Python) is desirable.

geeignet als

• Masterarbeit Physik der kondensierten Materie
• Masterarbeit Applied and Engineering Physics

Themensteller(in): Karsten Reuter