Chemical trends in the optical properties of rocksalt nanoparticles

The nature and magnitude of the optical gaps of rocksalt alkaline earth (MgO, CaO, SrO, MgS, MgSe) and transition metal chalcogenide (CdO, PbS) nanoparticles are studied using time-dependent density functional theory (TD-DFT) calculations on (MX)32 nanoparticles. We demonstrate, just as we previously showed for MgO, that TD-DFT calculations on rocksalt nanoparticles require the use of hybrid exchange–correlation (XC-)functionals with a high percentage of Hartree–Fock like exchange (e.g. BHLYP) or range-separated XC-functionals to circumvent problems related to the description of charge-transfer excitations. Concentrating on the results obtained with TD-BHLYP we show that the optical gap in rocksalt nanoparticles displays a wide range of behavior; ranging from large optical gaps stemming from a localized excitation involving corner atoms in alkaline earth oxides to a delocalized excitation and small optical gaps in the transition metal chalcogenides. Finally, we rationalize this wide range of behaviour in terms of differences in the degree to which the Coulombic interaction between the excited electron and hole is screened in the different nanoparticles, and relate it to the optical dielectric constants of the bulk materials the nanoparticles are made from

The generic mapping tools version 6

The Generic Mapping Tools (GMT) software is ubiquitous in the Earth and ocean sciences. As a cross-platform tool producing high-quality maps and figures, it is used by tens of thousands of scientists around the world. The basic syntax of GMT scripts has evolved very slowly since the 1990s, despite the fact that GMT is generally perceived to have a steep learning curve with many pitfalls for beginners and experienced users alike. Reducing these pitfalls means changing the interface, which would break compatibility with thousands of existing scripts. With the latest GMT version 6, we solve this conundrum by introducing a new "modern mode" to complement the interface used in previous versions, which GMT 6 now calls "classic mode." GMT 6 defaults to classic mode and thus is a recommended upgrade for all GMT 5 users. Nonetheless, new users should take advantage of modern mode to make shorter scripts, quickly access commonly used global data sets, and take full advantage of the new tools to draw subplots, place insets, and create animations.Funding Agency National Science Foundation (NSF) Appeared in article as U.S. National Science Foundation MSU Geological Sciences Endowmentinfo:eu-repo/semantics/publishedVersio

The Sequence of Events generator: A powerful tool for mission operations

The functions and features of the sequence of events (SOE) and flight operations procedures (FOP) generator developed and used at DLR/GSOC for the positioning of EUTELSAT 2 satellites are presented. The SOE and FOP are the main operational documents that are prepared for nominal as well as for non-nominal mission execution. Their structure and application are described. Both of these documents are generated, validated, and maintained by a common software tool. Its main features and advantages are demonstrated. The tool has been improved continuously over the last 5 years. Due to its flexibility it can easily be applied to other projects and new features may be added

Nachkriegsfeminismus in der sowjetischen Besatzungszone

Grit Bühler fokussiert in ihrer Studie über den Demokratischen Frauenbund Deutschland (DFD), der lange als staatsloyale Organisation der Sozialistischen Einheitspartei Deutschlands (SED) galt, die ersten feministischen Jahre und die Schlüsselfiguren, die in den Frauenausschüssen den Aufbruch stimulierten. Leitend ist geschlechter- und politikgeschichtlich die These des Nachkriegsfeminismus, wie sie in der Erforschung der Frauenausschüsse auch für die westlichen Besatzungszonen nach 1945 bekannt ist. Bühler beleuchtet, wie die Protagonistinnen unterschiedliche frauenpolitische Positionen als ‚schwesterliche Verbundenheit‘ in der Sowjetischen Besatzungszone zusammenbrachten, und die zunehmenden Interventionen der SED. Dabei wird erstmals die Anfangszeit des DFD als Teil der Geschichte der Frauenbewegung und des Feminismus in den Vordergrund gerückt

Engaging Students with Great Problems

The Great Problems Seminars were designed to bring first year engineering students into meaningful contact with current events, societal problems, and human needs. Key learning objectives include: introducing project team work and developing writing and presentation skills. Each seminar has focused on a large global issue: food and hunger, energy and its utilization, health and healthcare delivery, the NAE Grand Challenges. Seminars are co-taught by an interdisciplinary pair: one natural science/engineering instructor and one humanities/social science instructor. The first half of the two-term course sequence explores the depth and breadth of the problem; the second half is devoted to project work. Focus group assessment demonstrates that the GPS courses achieve the original course objectives. Student course evaluations indicate high satisfaction despite requiring significantly more work than traditional first year offerings taught within the disciplines. Comments by former GPS students demonstrate that they value how these courses prepared them for their futures

Optical excitation of MgO nanoparticles:a computational perspective

The optical absorption spectra of magnesium oxide (MgO) nanoparticles, along with the atomic centres responsible, are studied using a combination of time-dependent density functional theory (TD-DFT) and coupled-cluster methods. We demonstrate that TD-DFT calculations on MgO nanoparticles require the use of range-separated exchange–correlation (XC-) functionals or hybrid XC-functionals with a high percentage of Hartree–Fock like exchange to circumvent problems related to the description of charge-transfer excitations. Furthermore, we show that the vertical excitations responsible for the experimentally studied range of the spectra of the MgO nanoparticles typically involve both 3-coordinated corner sites and 4-coordinated edge sites. We argue therefore that to label peaks in these absorption spectra exclusively as either corner or edge features does not provide insight into the full physical picture