arXiv subjects

Henrik Dick

Publications and source records attributed to Henrik Dick.

3 recordsLinked to original sources

arXiv2026

Influence of Charge Density Waves on the Hall coefficient in NiTi

We present a mean-field charge density wave theory for NiTi using density functional theory bandstructure as a starting point. We calculate the Hall coefficient as a function of temperature and compare with recent experimental results. We analyze the contributions to the Hall coefficient from different parts of the Fermi surface and find that the Hall coefficient is dominated by certain ``hot spots''. The analysis shows that these hot spots are mostly dominated by Ni d-orbitals. We demonstrate that the Hall coefficient is not well reproduced by Boltzmann transport theory within the constant relaxation time approximation without charge density waves. We consider both uniaxial and biaxial charge density waves and show that biaxial charge density waves can account well for the Hall coefficient, while uniaxial cannot. We also investigate the temperature dependence of the resistivity and the specific heat.

cond-mat.mtrl-sci↗

arXiv2025

Optimization of Ab-Initio Based Tight-Binding Models

The electronic structure of solids can routinely be calculated by standard methods like density functional theory. However, in complicated situations like interfaces, grain boundaries or contact geometries one needs to resort to more simplified models of the electronic structure. Tight-binding models are using a reduced set of orbitals and aim to approximate the electronic structure by short range hopping processes. For example, maximally localized Wannier functions are often used for that purpose. However, their accuracy is limited by the need to disentangle the electronic bands. Here, we develop and investigate a different procedure to obtain tight-binding models inspired by machine-learning techniques. The model parameters are optimized in such a way as to reproduce ab-initio band structure data as accurately as possible using an as small as possible number of model parameters. The procedure is shown to result in models with smaller ranges and fewer orbitals than maximally localized Wannier functions but same or even better accuracy. We argue that such a procedure is more useful for automated construction of tight-binding models particularly for large-scale materials calculations.

cond-mat.mtrl-sci↗

arXiv2024

SIMULATeQCD: A simple multi-GPU lattice code for QCD calculations

The rise of exascale supercomputers has fueled competition among GPU vendors, driving lattice QCD developers to write code that supports multiple APIs. Moreover, new developments in algorithms and physics research require frequent updates to existing software. These challenges have to be balanced against constantly changing personnel. At the same time, there is a wide range of applications for HISQ fermions in QCD studies. This situation encourages the development of software featuring a HISQ action that is flexible, high-performing, open source, easy to use, and easy to adapt. In this technical paper, we explain the design strategy, provide implementation details, list available algorithms and modules, and show key performance indicators for SIMULATeQCD, a simple multi-GPU lattice code for large-scale QCD calculations, mainly developed and used by the HotQCD collaboration. The code is publicly available on GitHub.

hep-lat↗