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Humboldt-Universität zu Berlin - Faculty of Mathematics and Natural Sciences - Theory of excitations in low-dimensional systems

Research

Research Topics

We study light-matter interaction in low-dimensional materials from first principles. Below a list of our main research topics.

 

Excited-state properties of two-dimensional materials and heterostructures

We investigate electronic and optical exciations of two-dimensional materials and their heterostructures from first-principles methods based on density-functional theory (DFT) and many-body perturbation theory (MBPT - the GW approximation and the Bethe-Salpeter equation). Among our systems of interest there are graphene, hexagonal boron nitride (hBN), transition-metal dichalchogenices (TMDCs), and more.

Main collaborators:

Relevant publications: 

 

Optical nonlinearities from real-time time-dependent DFT

We study the interaction between light-absorbing materials and intense laser sources from real-time time-dependent DFT (RT-TDDFT). We adopted for the first time the Yabana-Bertsch to describe optical limiting in a prototypical macrocyclic molecule. Further applications and extensions of this approach are being carried out.

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Excitations from many-body perturbation theory: Methodology advances and developments

We work on advancements in the state-of-the-art methodology to calculate excited-state properties from MBPT, considering perturbations from the optical to the x-ray frequencies. Beyond the study of neutral excitations, such as electron-hole pairs, and the assessment of our methodology, we are developing new approaches to describe complex excited-state processes such as losses and scattering effects. 

Main collaborators:

  • Prof. Claudia Draxl, Dr. Dmitrii Nabok, Mr. Christian Vorwerk, Mr. Benjamin Aurich, Mr. Albin Hertrich, Mr. Bernhard Klett (HU Berlin).

Relevant publications: 

 

Excited states and polymorphism in organic materials

We study light-matter interaction in organic materials, such as molecular crystals and self-assembled monolayers. We are interested in understanding the interplay between the structure of these systems and the resulting electronic and optical properties, in view of describing excitations driven by visible light as well as x-ray radiation.

Main collaborators:

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Excitations in complex systems

We apply the above-mentioned methodologies to study excitation processes in realistic systems, in collaboration with experimental partners. Investigated materials range from inorganic solids like transparent conducting oxides (TCOs) and sulfides, to hybrid inorganic/organic systems and interfaces.

Main collaborators:

Relevant publications: