arXiv subjects

Christian König

Publications and source records attributed to Christian König.

4 recordsLinked to original sources

arXiv2025

Implementation Analysis of Collaborative Robot Digital Twins in Physics Engines

This paper presents a Digital Twin (DT) of a 6G communications system testbed that integrates two robotic manipulators with a high-precision optical infrared tracking system in Unreal Engine 5. Practical details of the setup and implementation insights provide valuable guidance for users aiming to replicate such systems, an endeavor that is crucial to advancing DT applications within the scientific community. Key topics discussed include video streaming, integration within the Robot Operating System 2 (ROS 2), and bidirectional communication. The insights provided are intended to support the development and deployment of DTs in robotics and automation research.

cs.RO↗

arXiv2022

Effect of strain and many-body corrections on the band inversions and topology of bismuth

The electronic band structure of Bi is calculated using state of the art electronic structure methods, including density functional theory and G$_0$W$_0$ quasiparticle approximations. The delicate ordering of states at the L point of the Brillouin zone, which determines the topological character of the electronic bands, is investigated in detail. The effect on the bands of strain, changing the structural parameters of the rhombohedral crystal structure, is shown to be important in determining this ordering and the resulting topological character.

cond-mat.mtrl-sci↗

arXiv2022

Electronic properties of bismuth nanostructures

The passivation of thin Bi(1 1 1) films with hydrogen and oxide capping layers is investigated from first principles. Considering termination-related changes of the crystal structure, we show how the bands and density of states are affected. In the context of the much discussed semimetal-to-semiconductor transition and the band topology of the bulk material, we consider the effects of confinement in the whole Brillouin zone and go beyond standard density functional theory by including many-body interactions via the G$_0$W$_0$ approximation. The conductivity of unterminated films is calculated via the Boltzmann transport equation using the simple constant relaxation time approximation and compared to experimental observations that have suggested a two-channel model.

cond-mat.mtrl-sci↗

arXiv2019

Structural modification of thin Bi(1 1 1) films by passivation and native oxide model

The structure of thin terminated Bi(1 1 1) films of approximately 1 nm thickness is investigated from first principles. Our density functional theory calculations show that covalent bonds to the surface can change the orientation of the films completely. For thicker films, the effect is limited to the surface only. Based on these observations, we further present a simple model structure for the native oxide and chemically similar oxides, which form a protective capping layer, leaving the orientation of the films unchanged. The advantages of this energetically favorable layered termination are discussed in the context of the films' technological exploitation in nanoelectronic devices.

cond-mat.mtrl-sci↗