Projects of users of the HPC service
A selection of projects from different disciplines:
New approach to synthetic production of natural substances developed
The use of computer simulations opened up a detailed insight into the molecular mechanisms involved in isolonic pegide formation. The application of modern computer chemistry techniques was made possible in particular by calculations on the DFG-funded supercomputer CHEOPS.
Publication: Qi Zhang, J. Rinkel, B. Goldfuss, J. Dickschat, K. Tiefenbacher: Sesquiterpene cyclizations catalyzed inside the resorcinarene capsule and application in the short synthesis of isolongifolene and isologifolenone. In: Nature Catalysis Volume 1 (2018), p. 609–615
Ideal GLM-MHD: About the entropy consistent nine-wave magnetic field divergence diminishing ideal magnetohydrodynamics equations
From the abstract: The paper presents two contributions in the context of the numerical simulation of magnetized fluid dynamics. First, we show how to extend the ideal magnetohydrodynamics (MHD) equations with an inbuilt magnetic field divergence cleaning mechanism in such a way that the resulting model is consistent with the second law of thermodynamics. As a byproduct of these derivations, we show that not all of the commonly used divergence cleaning extensions of the ideal MHD equations are thermodynamically consistent. Secondly, we present a numerical scheme obtained by constructing a specific finite volume discretization that is consistent with the discrete thermodynamic entropy.
Publication: D.Derigs, A. Winters, G. Gassner, S. Walch, M. Bohm In: Journal of Computational Physics Volume 364 (07/2018), p. 420-467
Cobalt-catalyzed C–H cyanations: Insights into the reaction mechanism and the role of London dispersion
From the abstract: Carboxylate-assisted cobalt(III)-catalyzed C–H cyanations are highly efficient processes for the synthesis of (hetero)aromatic nitriles. We have now analyzed the cyanation of differently substituted 2-phenylpyridines in detail computationally by density functional theory and also experimentally. Based on our investigations, we propose a plausible reaction mechanism for this transformation that is in line with the experimental observations. Additional calculations, including NCIPLOT, dispersion interaction densities, and local energy decomposition analysis, for the model cyanation of 2-phenylpyridine furthermore highlight that London dispersion is an important factor that enables this challenging C–H transformation.
Publication: E. Detmar, V. Müller, D. Zell, L. Ackermann, M. Breugst In: Beilstein Journal of Organic Chemistry Volume 14 (2018), p.1537–1545.
Two-stage multipolar ordering in Pr T2 Al20 Kondo materials
From the abstract: Pr T2 Al20. Among heavy fermion materials, there is a set of rare-earth intermetallics with non-Kramers Pr3+ 4f2 moments which exhibit a rich phase diagram with intertwined quadrupolar orders, superconductivity, and non-Fermi liquid behavior. However, more subtle broken symmetries such as multipolar orders in these Kondo materials remain poorly studied. Here, we argue that multi-spin interactions between local moments beyond the conventional two-spin exchange must play an important role in Kondo materials near the ordered to heavy Fermi liquid transition. We show that this drives a plethora of phases with coexisting multipolar orders and multiple thermal phase transitions, providing a natural framework for interpreting experiments on the Pr(T)2 Al20 class of compounds.
Publication: F. Freyer, J. Attig, SungBin Lee, A. Paramekanti, S. Trebst, and Yong Baek Kim In: Physical Review B Vol. 97, Iss. 11-15 March 2018
A comparative study on polynomial dealiasing and split form discontinuous Galerkin schemes for under-resolved turbulence computations
From the abstract: "This work focuses on the accuracy and stability of high-order nodal discontinuous Galerkin (DG) methods for under-resolved turbulence computations. In particular we consider the inviscid Taylor-Green vortex (TGV) flow to analyse the implicit large eddy simulation (iLES) capabilities of DG methods at very high Reynolds numbers."
Publikation: A. Winters, R. Moura, G. Mengaldo, G. Gassner, S. Walch, J. Peiro, S. Sherwin In: Journal of Computational Physics, Volume 372 (2018), p. 1-21.
Integrative genomic profiling of large-cell neuroendocrine carcinomas reveals distinct subtypes of high-grade neuroendocrine lung tumors
From the abstract: Pulmonary large-cell neuroendocrine carcinomas (LCNECs) have similarities with other lung cancers, but their precise relationship has remained unclear. Here we perform a comprehensive genomic (n = 60) and transcriptomic (n = 69) analysis of 75 LCNECs and identify two molecular subgroups: “type I LCNECs” with bi-allelic TP53 and STK11/KEAP1 alterations (37%), and “type II LCNECs” enriched for bi-allelic inactivation of TP53 and RB1 (42%).
Publication: P. Nürnberg, et al. In: Nature Communications Volume 9 (2018), Article number 1048
Quantum Spin Liquids in Frustrated Spin-1 Diamond Antiferromagnets
From the abstract: "Motivated by the recent synthesis of the spin-1 A-site spinel NiRh2O4, we investigate the classical to quantum crossover of a frustrated J1-J2 Heisenberg model on the diamond lattice upon varying the spin length S. Applying a recently developed pseudospin functional renormalization group approach for arbitrary spin-S magnets, we find that systems with S ≥ 3=2 reside in the classical regime, where the lowtemperature physics is dominated by the formation of coplanar spirals and a thermal (order-by-disorder) transition."
Publication: F. Buessen, M. Hering, J. Reuther, S. Trebst In: Physical Review Letters 120 (2018)
Activating de novo mutations in NFE2L2 encoding NRF2 cause a multisystem disorder
From the abstract: "Transcription factor NRF2, encoded by NFE2L2, is the master regulator of defense against stress in mammalian cells. Somatic mutations of NFE2L2 leading to NRF2 accumulation promote cell survival and drug resistance in cancer cells. Here we show that the same mutations as inborn de novo mutations cause an early onset multisystem disorder with failure to thrive, immunodeficiency and neurological symptoms. NRF2 accumulation leads to widespread misregulation of gene expression and an imbalance in cytosolic redox balance."
Publication: P. Nürnberg, et al. In: Nature Communications Volume 8 (2017), Article number 818
Ocean of salt water under the ice crust of Jupiter's moon Ganymeds
This revealed observations of the auroras of Jupiter's moon using the Hubble Space Telescope. The observations measured the impact a saltwater ocean has on the rocking of the auroras. They were carried out and evaluated by a team of scientists led by Professor Dr. Joachim Saur from the Institute of Geophysics and Meteorology at the University of Cologne. "The effect of weakening by Ganymed's ocean is so strong that the rocking of the auroral vals from 6 degrees without ocean is attenuated to the observed 2 degrees," explains Stefan Duling of the Institute of Geophysics and Meteorology, who, as part of his master's thesis, Implemented and implemented accompanying computer models. The calculations were done on CHEOPS.
Publication: J. Saur, et al.: The search for asubsurface ocean in Ganymede with Hubble Space Telescope observations of its auroral ovals. In: Journal of Geophysical Research: Space Physics 120 (2015), p. 1715–1737
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