arXiv subjects

Tobias Burnus

Publications and source records attributed to Tobias Burnus.

4 recordsLinked to original sources

arXiv2022

ECP SOLLVE: Validation and Verification Testsuite Status Update and Compiler Insight for OpenMP

The OpenMP language continues to evolve with every new specification release, as does the need to validate and verify the new features that have been introduced. With the release of OpenMP 5.0 and OpenMP 5.1, plenty of new target offload and host-based features have been introduced to the programming model. While OpenMP continues to grow in maturity, there is an observable growth in the number of compiler and hardware vendors that support OpenMP. In this manuscript, we focus on evaluating the conformity and implementation progress of various compiler vendors such as Cray, IBM, GNU, Clang/LLVM, NVIDIA, Intel and AMD. We specifically address the 4.5, 5.0, and 5.1 versions of the specification.

cs.DC↗

arXiv2012

Electronic properties of graphene nanoribbons under gate electric fields

Quantum-dot states in graphene nanoribbons (GNR) were calculated using density-functional theory, considering the effect of the electric field of gate electrodes. The field is parallel to the GNR plane and was generated by an inhomogeneous charge sheet placed atop the ribbon. Varying the electric field allowed to observe the development of the GNR states and the formation of localized, quantum-dot-like states in the band gap. The calculation has been performed for armchair GNRs and for armchair ribbons with a zigzag section. For the armchair GNR a static dielectric constant of ε approx. 4 could be determined.

cond-mat.mes-hall↗

arXiv2012

Libxc: a library of exchange and correlation functionals for density functional theory

The central quantity of density functional theory is the so-called exchange-correlation functional. This quantity encompasses all non-trivial many-body effects of the ground-state and has to be approximated in any practical application of the theory. For the past 50 years, hundreds of such approximations have appeared, with many successfully persisting in the electronic structure community and literature. Here, we present a library that contains routines to evaluate many of these functionals (around 180) and their derivatives.

cond-mat.mtrl-sci↗

arXiv2005

Time-dependent electron localization function

In this article we present a generalization of the electron localization function (ELF) that can be used to analyze time-dependent processes. The time-dependent ELF allows the time-resolved observation of the formation, the modulation, and the breaking of chemical bonds, and can thus provide a visual understanding of complex reactions involving the dynamics of excited electrons. We illustrate the usefulness of the time-dependent ELF by two examples: the pi-pi* transition induced by a laser field, and the destruction of bonds and formation of lone pairs in a scattering process.

physics.chem-ph↗