New Strategies in Modeling Electronic Structures and Properties with Applications to Actinides

This chapter discusses contemporary quantum chemical methods and provides general insights into modern electronic structure theory with a focus on heavy-element-containing compounds. We first give a short overview of relativistic Hamiltonians that are frequently applied to account for relativistic effects. Then, we scrutinize various quantum chemistry methods that approximate the $N$-electron wave function. In this respect, we will review the most popular single- and multi-reference approaches that have been developed to model the multi-reference nature of heavy element compounds and their ground- and excited-state electronic structures. Specifically, we introduce various flavors of post-Hartree--Fock methods and optimization schemes like the complete active space self-consistent field method, the configuration interaction approach, the Fock-space coupled cluster model, the pair-coupled cluster doubles ansatz, also known as the antisymmetric product of 1 reference orbital geminal, and the density matrix renormalization group algorithm. Furthermore, we will illustrate how concepts of quantum information theory provide us with a qualitative understanding of complex electronic structures using the picture of interacting orbitals. While modern quantum chemistry facilitates a quantitative description of atoms and molecules as well as their properties, concepts of quantum information theory offer new strategies for a qualitative interpretation that can shed new light onto the chemistry of complex molecular compounds.Comment: 43 pages, 3 figures, Version of Recor

Forschung mit Wissenstransfer erhöht die Praxiswirkung : Serie Systemvergleich Hohenrain II

Im Projekt «Optimierung der Milchproduktion mit frischem Wiesenfutter» war der Wissenstransfer zwischen Praxis, Forschung sowie Bildung und Beratung ein zentrales Anliegen. Besondere Bedeutung hatten dabei die Arbeitskreise der beteiligten Praxisbetriebe. Sie lieferten einerseits die Grundlagen und Daten für die Bearbeitung von Forschungsfragen und beschäftigten sich andererseits intensiv mit der Umsetzung von neuen Vorgehensweisen. Dies löste auf den Betrieben zahlreiche Innovationen aus und unterstützte insbesondere den Transfer von Wissen in konkrete Handlungen. Damit diese Wirkung eintritt, müssen wichtige Voraussetzungen berücksichtigt werden: Es bedingt eine sorgfältige Auswahl von Betrieben mit einer hohen Motivation und Bereitschaft für den offenen Austausch untereinander. Weitere Erfolgsfaktoren sind die intensive Begleitung durch Projektverantwortliche und ganz besonders durch Moderationspersonen als wichtige Drehscheibe der Kommunikation zwischen den Beteiligten. Die Kombination dieser Faktoren stellt hohe Anforderungen an alle Beteiligten und wurde in diesem Projekt in einem hohen Masse erreicht, wie unsere Untersuchungen zeigen

Formation of [Ru(NHC)₄(η²-O₂)H] ⁺:An unusual, high frequency hydride chemical shift and facile, reversible coordination of O₂

(Chemical Equation Presented) Reaction of the purple tetrakiscarbene ruthenium cation [Ru(IiPr2Me2) 4H]+ (1, IiPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with oxygen affords the pink η2-O2 hydride species [Ru(IiPr 2Me2)4(η2-O2)H] + (2). 2 displays (i) a very facile, reversible O2 coordination and (ii) an unexpectedly positive hydride chemical shift, and both these features can be predicted and explained by density functional theory (DFT) calculations.</p

Formation of [Ru(NHC)₄(η²-O₂)H] ⁺:An unusual, high frequency hydride chemical shift and facile, reversible coordination of O₂

(Chemical Equation Presented) Reaction of the purple tetrakiscarbene ruthenium cation [Ru(IiPr2Me2) 4H]+ (1, IiPr2Me2 = 1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with oxygen affords the pink η2-O2 hydride species [Ru(IiPr 2Me2)4(η2-O2)H] + (2). 2 displays (i) a very facile, reversible O2 coordination and (ii) an unexpectedly positive hydride chemical shift, and both these features can be predicted and explained by density functional theory (DFT) calculations.</p

Unstationary aspects of foehn in a large valley part I: operational setup, scientific objectives and analysis of the cases during the special observing period of the MAP subprogramme FORM

The Rhine valley, which stretches from the main Alpine crest to the Lake of Constance, was chosen as the target area to study unstationary aspects of foehn during the Special Observing Period (SOP) of the Mesoscale Alpine Programme (MAP). This large valley is up to 10?km wide and has some of the highest foehn frequencies in the European Alps. The MAP subprogram FORM (FOehn in the Rhine valley during MAP) was designed to investigate various aspects of the foehn including the interaction of foehn flow with the boundary layer and the processes that remove the cold air pool. The subprogram was also focused on improving the understanding and forecasting of foehn-related phenomena such as waves and turbulence. A large number of in-situ and remote sensing observing systems were deployed to take measurements during the field phase of MAP. Among them were about 50 surface stations, up to 9 radiosonde stations, 2 wind profilers, 4 Doppler sodars, 2 scintillometers, 1 scanning and 1 backscatter lidar and different research aircraft. This paper gives an overview of the objectives of FORM, describes the target area and its instrumentation, and provides a detailed synoptic description of the 12 foehn cases observed during the MAP SOP