Theoretical Study of Substitution of Si for Ge in Mn5\text{}_{5}Ge3\text{}_{3}

The substitution of silicon for germanium in Mn$\text{}_{5}$Ge$\text{}_{3}$ leads to a decrease in the magnetization for x < 0.7 and then to phase transition toward a non-collinear antiferromagnetic order for Mn$\text{}_{5}$Si$\text{}_{3}$. The magnetic properties of Mn$\text{}_{5}$Ge$\text{}_{3}$ and Mn$\text{}_{5}$(Ge$\text{}_{0.5}$Si$\text{}_{0.5}$)$\text{}_{3}$ are analyzed by means of band structure calculations

Vacancy formation in

The defect population is important for understanding the microstructure of δ-plutonium. Using spin-polarized density-functional theory, we calculate the formation energies of monovacancies as well as divacancies. We show that the unrelaxed values are quite independent of the magnetic configuration while atomic relaxations lead to smaller values, relaxation effects being larger for the disordered magnetic structure

The electronic and magnetic properties of Fe3_3N

The electronic and magnetic properties of the ferromagnetic nitride Fe$_3$N were investigated by use of the ASW method. The calculations were done in two different crystal structures : the experimental-hexagonal one and a hypothetical Cu$_3$Au-type one- in order to correlate the magnetic structure of Fe$_3$N with that of its homologues Fe$_3$X (X = non-metal). Results were assessed in connection with existing experimental data (magnetic measurements, Mössbauer resonance). Independently of the structure, densities of states due to the iron-nitrogen bond are introduced at Fermi level and should play a role in the magnetism of the nitride.Les propriétés électroniques et magnétiques du nitrure ferromagnétique Fe$_3$N ont été étudiées par la méthode de l'onde sphérique augmentée ASW. Les calculs ont été effectués dans deux structures cristallines différentes : les structures hexagonale (expérimentale) et Cu$_3$Au (hypothétique) afin d'établir des corrélations entre la structure magnétique de Fe$_3$N et celle de ses homologues Fe$_3$X (X = non-métal). Les résultats sont discutés en connection avec des résultats expérimentaux (mesures d'aimantation, résonance Mössbauer). Indépendamment de la structure, des densités d'états dues à la liaison fer-azote sont introduites au niveau de Fermi et devraient jouer un rôle dans le magnétisme du nitrure

Theoretical and experimental refraction index of shock compressed and pre-compressed water in the megabar pressure range

The refraction index of water at megabar pressures was calculated ab initio with the quantum molecular dynamics (QMD) package ABINIT using the projector augmented (PAW) formalism. Calculations were compared to experimental results obtained by laser-driven shocks on water in standard conditions and on water samples statically precompressed at ${\approx}10\ \text{kBar}$ . The refraction index was measured in transparent and opaque states of water using a VISAR diagnostics. We also modelled the data using an extended Lorentz-Drude model. At high compressions, a strong increase of the refraction index is observed both in experimental results and in the theoretical calculations, which is an indication of water approaching band gap closure

The calculated electronic and magnetic structures of Fe4N and Mn 4N

Using the augmented spherical wave method (A.S.W.) we calculate the electronic and magnetic structures of Fe4N and Mn4N. Both nitrides are found to order magnetically exhibiting ferro- and ferrimagnetic spin alignment respectively. The magnetic moments found are in good agreement with neutron data. Both systems can be described via covalent magnetism. A comparison with Goodenough's phenomenological model as well as with Heusler alloys is given.Utilisant la méthode de l'« onde sphérique augmentée » (augmented spherical wave) les auteurs ont calculé les structures électroniques et magnétiques de Fe4N et de Mn4N. Les deux nitrures s'ordonnent magnétiquement avec un alignement ferro- et ferri-magnétique respectivement. Les valeurs obtenues des moments magnétiques sont en bon accord avec celles de la littérature. Une comparaison avec le modèle phénoménologique de Goodenough ainsi qu'avec les alliages de Heusler est donnée

MareyMap online: A user-friendly web application and database service for estimating recombination rates using physical and genetic maps

Given the importance of meiotic recombination in biology, there is a need to develop robust methods to estimate meiotic recombination rates. A popular approach, called the Marey map approach, relies on comparing genetic and physical maps of a chromosome to estimate local recombination rates. In the past, we have implemented this approach in an R package called MareyMap, which includes many functionalities useful to get reliable recombination rate estimates in a semi-automated way. MareyMap has been used repeatedly in studies looking at the effect of recombination on genome evolution. Here, we propose a simpler user-friendly web service version of MareyMap, called MareyMap Online, which allows a user to get recombination rates from her/his own data or from a publicly available database that we offer in a few clicks. When the analysis is done, the user is asked whether her/his curated data can be placed in the database and shared with other users, which we hope will make meta-analysis on recombination rates including many species easy in the future

Local spin density functional investigations of a manganite with perovskite-type derived structures

The electronic and magnetic structures of the perovskite CaMnO3 are self-consistently calculated assuming two crystal structures at the same formula unit volume within the local spin density functional theory and the augmented spherical wave (ASW) method. From the comparisons of energy differences between the different magnetic states the ground state configuration is an insulator with G-type ordering. This result together with the magnitudes of the magnetic moments are in agreement with experiment. The influence of mixing between Mn and O is found spin dependent from the analysis of the crystal orbital overlap population (COOP) which enable to describe the chemical bond. The calculations underline a feature of a half metallic ferromagnet which could be connected with the colossal magnetoresistance (CMR) property of related compounds

Influence of vector spatial dispersal on virulence evolution and prevalence of pathogen in stochastic environment, example of Chagas disease

Remerciements ECOFEC