First principles calculations of band offsets at heterovalent ε\varepsilon-Ge/Inx_xAl1−x_{1-x}As interfaces

First principles electronic structure calculations are carried out to investigate the band alignments of tensile strained (001) Ge interfaced with (001) In$_{x}$Al$_{1-x}$As. The sensitivities of band offsets to interfacial structure, interfacial stoichiometry, and substrate stoichiometry, are investigated. Large qualitative variations of the valence and conduction band offsets are observed, including changes of the band offset type, indicating the importance of local structural variations of the interface for band offsets in real samples. Our results explain recent measurements of band offsets derived from XPS core level spectra in terms of As atoms penetrating through the first few monolayers of the Ge film. Analogous studies are carried out for the diffusion of other species across the interface, and in general the band offsets vary approximately linearly with diffusion depth relative to the values for pristine "sharp" interfaces, where the sign of the linear variation depends on the diffusing species. This large sensitivity of the band alignments to interface details indicates potential routes to chemically control the band offset of this group IV/III-V interface by tuning the stoichiometry of the substrate surface that the thin film is grown on.Comment: 12 pages, 10 figure

Floquet formulation of the dynamical Berry-phase approach to non-linear optics in extended systems

We present a Floquet scheme for the ab-initio calculation of nonlinear optical properties in extended systems. This entails a reformulation of the real-time approach based on the dynamical Berry-phase polarisation [Attaccalite & Gr\"uning, PRB 88, 1-9 (2013)] and retains the advantage of being non-perturbative in the electric field. The proposed method applies to periodically-driven Hamiltonians and makes use of this symmetry to turn a time-dependent problem into a self-consistent time-independent eigenvalue problem. We implemented this Floquet scheme at the independent particle level and compared it with the real-time approach. Our reformulation reproduces real-time-calculated $2^{nd}$ and $3^{rd}$ order susceptibilities for a number of bulk and two-dimensional materials, while reducing the associated computational cost by one or two orders of magnitude

Measuring Six Facets of Curiosity in Germany and the UK: A German-Language Adaptation of the 5DCR and Its Comparability with the English-Language Source Version

The five-dimensional curiosity-scale revised (5DCR) by Kashdan et al. (Citation2020) is the most comprehensive curiosity inventory available to date. 5DCR measures six facets of curiosity with four items each. Here, we present a German-language adaptation of the 5DCR and comprehensively validate this adaptation in a diverse sample of adults from Germany (N = 486). Moreover, we provide new evidence on the original English-language 5DCR in a parallel sample from the UK (N = 483). In both countries, we investigate the six facets' reliability, factorial validity, and convergent and discriminant validity with a large set of individual-differences constructs. In addition, we analyze the measurement invariance of the curiosity facets across the UK and Germany and across socio-demographic subgroups defined by age, sex, and education. Findings demonstrate that the new German-language adaptation of 5DCR and its English-language source version show psychometric properties similar to the original studies by Kashdan et al. (Citation2020) in the United States. All six curiosity facets reach at least partial scalar invariance across cultures, sex, education, and mostly also across age groups. The findings support the six-faceted theory of curiosity and show that 5DCR allows for a valid assessment of curiosity across cultures

Two Avenues to Self-Interaction Correction within Kohn-Sham Theory: Unitary Invariance is the Shortcut

The most widely-used density functionals for the exchange-correlation energy are inexact for one-electron systems. Their self-interaction errors can be severe in some applications. The problem is not only to correct the self-interaction error, but to do so in a way that will not violate size-consistency and will not go outside the standard Kohn-Sham density functional theory. The solution via the optimized effective potential (OEP) method will be discussed, first for the Perdew-Zunger self-interaction correction (whose performance for molecules is briefly summarized) and then for the more modern self-interaction corrections based upon unitarily-invariant indicators of iso-orbital regions. For the latter approaches, the OEP construction is greatly simplified. The kinetic-energy-based iso-orbital indicator \tau^W_\sigma(\re)/\tau_\sigma(\re) will be discussed and plotted, along with an alternative exchange-based indicator

Measuring Intellectual Curiosity across Cultures: Validity and Comparability of a New Scale in Six Languages

Intellectual curiosity - the tendency to seek out and engage in opportunities for effortful cognitive activity - is a crucial construct in educational research and beyond. Measures of intellectual curiosity vary widely in psychometric quality, and few measures have demonstrated validity and comparability of scores across multiple languages. We analyzed a novel, six-item intellectual curiosity scale (ICS) originally developed for cross-national comparisons in the context of the OECD's Programme for the International Assessment of Adult Competencies (PIAAC). Samples from six countries representing six national languages (U.S. Germany, France, Spain, Poland, and Japan; total N = 5,557) confirmed that the ICS possesses very good psychometric properties. The scale is essentially unidimensional and showed excellent reliability estimates. On top of factorial validity, the scale demonstrated strict measurement invariance across demographic segments (gender, age groups, and educational strata) and at least partial scalar invariance across countries. As per its convergent and divergent associations with a broad range of constructs (e.g., Open-Mindedness and other Big Five traits, Perseverance, Sensation Seeking, Job Orientations, and Vocational Interests), it also showed convincing construct validity. Given its internal and external relationships, we recommend the ICS for assessing intellectual curiosity, especially in cross-cultural research applications, yet we also point out future research areas

Warburg effect and translocation-induced genomic instability: two yeast models for cancer cells

Yeast has been established as an efficient model system to study biological principles underpinning human health. In this review we focus on yeast models covering two aspects of cancer formation and progression (i) the activity of pyruvate kinase (PK), which recapitulates metabolic features of cancer cells, including the Warburg effect, and (ii) chromosome bridge-induced translocation (BIT) mimiking genome instability in cancer. Saccharomyces cerevisiae is an excellent model to study cancer cell metabolism, as exponentially growing yeast cells exhibit many metabolic similarities with rapidly proliferating cancer cells. The metabolic reconfiguration includes an increase in glucose uptake and fermentation, at the expense of respiration and oxidative phosphorylation (the Warburg effect), and involves a broad reconfiguration of nucleotide and amino acid metabolism. Both in yeast and humans, the regulation of this process seems to have a central player, PK, which is up-regulated in cancer, and to occur mostly on a post-transcriptional and post-translational basis. Furthermore, BIT allows to generate selectable translocation-derived recombinants ("translocants"), between any two desired chromosomal locations, in wild-type yeast strains transformed with a linear DNA cassette carrying a selectable marker flanked by two DNA sequences homologous to different chromosomes. Using the BIT system, targeted non-reciprocal translocations in mitosis are easily inducible. An extensive collection of different yeast translocants exhibiting genome instability and aberrant phenotypes similar to cancer cells has been produced and subjected to analysis. In this review, we hence provide an overview upon two yeast cancer models, and extrapolate general principles for mimicking human disease mechanisms in yeast

Matching the BRIC equity premium: A structural approach

The equity risk premium (ERP) in BRIC markets is, on average, significantly higher than that in the US market. This paper employs an endowment economy with recursive preferences and long-run risk to explain the ERP generated by a portfolio of BRIC equity indices. The combination of recursive preferences and long-run risk partially explains the BRIC ERP. It turns out that there is a puzzle with respect to BRIC data as well. This holds even if we account for high levels of aversion to consumption and utility risk and for the empirically observed autoregressive structure of US consumption and BRIC dividend growth. (C) 2014 Elsevier B.V. All rights reserved

Reactions of (-)-sparteine with alkali metal HMDS complexes : conventional meets the unconventional

Conventional (-)-sparteine adducts of lithium and sodium 1,1,1,3,3,3-hexamethyldisilazide (HMDS) were prepared and characterised, along with an unexpected and unconventional hydroxyl-incorporated sodium sodiate, [(-)-sparteine·Na(-HMDS)Na·(-)-sparteine]+[Na4(-HMDS)4(OH)]--the complex anion of which is the first inverse crown ether anion

Microscopic modeling of photoluminescence of strongly disordered semiconductors

A microscopic theory for the luminescence of ordered semiconductors is modified to describe photoluminescence of strongly disordered semiconductors. The approach includes both diagonal disorder and the many-body Coulomb interaction. As a case study, the light emission of a correlated plasma is investigated numerically for a one-dimensional two-band tight-binding model. The band structure of the underlying ordered system is assumed to correspond to either a direct or an indirect semiconductor. In particular, luminescence and absorption spectra are computed for various levels of disorder and sample temperature to determine thermodynamic relations, the Stokes shift, and the radiative lifetime distribution.Comment: 35 pages, 14 figure

Density Functional Theory Approach to Noncovalent Interactions via Interacting Monomer Densities

A recently proposed "DFT+dispersion" treatment (Rajchel et al., Phys. Rev. Lett., 2010, 104, 163001) is described in detail and illustrated by more examples. The formalism derives the dispersion-free density functional theory (DFT) interaction energy and combines it with the dispersion energy from separate DFT calculations. It consists in the self-consistent polarization of DFT monomers restrained by the exclusion principle via the Pauli blockade technique. Within the monomers a complete exchange-correlation potential should be used, but between them only the exact exchange operates. The applications to wide range of molecular complexes from rare-gas dimers to H-bonds to pi-electron interactions show good agreement with benchmark values.Comment: 9 pages, 5 figures, 2 tables, REVTeX