COMPUTATIONAL PHYSICS AND MATERIALS THEORY

Calculation of materials properties that is based on a description of their electronic structure can be mathematically very complicated, however within the framework of density functional theory it suffices to know the average number of electrons located at any one point in space, i.e., the electron density. The development and use of quantum mechanical methods based on density functional theory and related approaches enable more efficient and accurate calculations of the ground and excited states of known and not-yet-synthesized molecules and materials. They are used for example to elucidate the movement and interactions of the charge carriers that govern photochemical processes and the dielectric response of electrochemical systems. Monte Carlo, molecular dynamics, and a range of other physics-based simulation techniques are also used to sample the states of such physical systems.

Sampling the photo-chemical oxidation of
methoxy on titania with femtosecond resolution (A-hole, B-electron).

PHYSICS IN 2D: GRAPHENE AND LAYERED MATERIALS

The possibility to fabricate 2D device architectures with desired combinations of graphene-like materials has posed fundamental questions about their physics and chemistry. As an extreme case in surface science, graphene and layered materials like transition metal chalcogenides (e.g. SnS, MoS₂, WSe₂) exploit physics that cannot be derived by scaling down the associated bulk structures and phenomena. Combining the properties of these 2D layers opens almost unlimited possibilities for novel devices with tailor-made electronic, optical, magnetic, thermal, and mechanical properties with applications ranging from energy to quantum technologies. Materials modeling and simulation can be used for example to provide insights into the physics of Moiré assemblies and guide their design.

Probing unconventional electronic behavior in
twisted multi-layer graphene.

BASIC ENERGY SCIENCE

Significantly enhancing the performance of devices and systems for energy conversion and storage most often critically depends on the introduction of novel materials with tailored functionality. The use of theoretical concepts and materials models that describe important physical and chemical processes, from atoms to device components, reduce uncertainty in the lab and expedite the development of various energy technologies such as photovoltaics, batteries, and thermoelectrics. On the basis of quantum mechanical calculations for example it is possible to accurately predict the course of chemical transformations of important fuels and produce reliable descriptions of the electronic excitations induced by light pertinent to the conversion of solar energy into secondary energy sources, while offering practioners a reliable reference for interpreting spectroscopy.

Obtaining atomistic insights into diffusion-induced fracture in
silicon-based Li-ion battery electrodes.