LAPW vs. LMTO full-potential simulations and anharmonic dynamics of KNbO3

With the aim to get an insight in the origin of differences in the earlier reported calculation results for KNbO3 and to test the recently proposed implementation of the FP-LMTO method by Methfessel and van Schilfgaarde, we perform a comparative study of the ferroelectric instability in KNbO3 by FP-LMTO and LAPW methods. It is shown that a high precision in the description of the charge density variations over the interstitial region in perovskite materials is essential; the technical limitations of the accuracy of charge-density description apparently accounted for previously reported slight disagreement with the LAPW results. With more accurate description of the charge density by sufficiently fine real-space grid, the results obtained by both methods became almost identical. In order to extract additional information (beyond the harmonic approximation) from the total energy fit obtainable in total-energy calculations, a scheme is proposed to solve the multidimensional vibrational Schroedinger equation in the model of non-interacting anharmonic oscillators via the expansion in hyperspherical harmonics.Comment: 11 pages, 2 figures, uses aipproc.sty. Presented at the Fifth Williamsburg Workshop on First-Principles Calculations for Ferroelectric

The stratification of regolith on celestial objects

All atmosphere-less planetary bodies are covered with a dust layer, the so-called regolith, which determines the optical, mechanical and thermal properties of their surface. These properties depend on the regolith material, the size distribution of the particles it consists of, and the porosity to which these particles are packed. We performed experiments in parabolic flights to determine the gravity dependency of the packing density of regolith for solid-particle sizes of 60 $\mu$m and 1 mm as well as for 100-250 $\mu$m-sized agglomerates of 1.5 $\mu$m-sized solid grains. We utilized g-levels between 0.7 m s$^{-2}$ and 18 m s$^{-2}$ and completed our measurements with experiments under normal gravity conditions. Based on previous experimental and theoretical literature and supported by our new experiments, we developed an analytical model to calculate the regolith stratification of celestial rocky and icy bodies and estimated the mechanical yields of the regolith under the weight of an astronaut and a spacecraft resting on these objects.Comment: 15 pages, 12 figure

Ab initio Calculations for SrTiO_3 (100) Surface Structure

Results of detailed calculations for SrTiO_3 (100) surface relaxation and the electronic structure for the two different terminations (SrO and TiO_2) are discussed. These are based on ab initio Hartree-Fock (HF) method with electron correlation corrections and Density Functional Theory (DFT) with different exchange-correlation functionals, including hybrid (B3PW, B3LYP) exchange techniques. Results are compared with previous ab initio plane wave LDA calculations. All methods agree well on both surface energies and on atomic displacements. Considerable increase of Ti[Single Bond]O chemical bond covalency nearby the surface is predicted, along with a gap reduction, especially for the TiO_2 termination

Interest rate pass-through in Germany and the euro area

This paper analyzes the interest rate pass-through for Germany and the euro area using for the first time a fully harmonized data set on bank retail rates. In a vector error correction model, the speed and completeness of the pass-through from market rates to bank interest rates are estimated for the period January 2003 to September 2007. We find that time deposit and corporate loan rates other than overdrafts adapt relatively fast to changes in refinancing costs, followed by rates for private housing loans. On the contrary, especially longer term consumer lending rates and rates for savings deposits show the most sluggish pass-through behavior. In contrast to earlier studies, results for Germany and the euro area excluding Germany are similar by and large. We therefore conclude that differences in the pass-through behavior seem to be associated rather with certain banking products than with cross-country differences

Desarrollo, desigualdad social y la unidad de América Latina.

Estudios sobre cuestiones de interpretación de la desigualdad social, la pobreza y la exclusión en las sociedades latinoamericanas, relativas al proceso de desarrollo, la precariedad del trabajo, las condiciones de pobreza urbana y rural, el saneamiento, los nuevos pobres, la ruptura de lazos familiares y sociales indican la urgencia de un rumbo a tomarse, así como oportunidades y alternativas para su reducción, superación y redefinición de las políticas públicas en América Latina. En tal contexto, este artículo tiene por meta plantear un debate teórico y reflexivo que lleve a la comprensión de las circunstancias y las prácticas sociales; creemos que dicha situación da lugar a la reproducción de la pobreza continua, alimentada por la creciente exclusión social, la dinámica económica de producto dominante en el pasado, en razón de décadas de políticas neoliberales, así como por los sistemas democráticos y la lucha por los derechos fundamentales al desarrollo en América Latina en las últimas décadas, desde los años noventa y principios del siglo XXI

Evading terror? Terror Attacks and Internal Migration in Israel

This paper empirically analyses the relationship between terror incidents and internal migration in Israel. Using a newly created database of region-to-region migration flows for the years 1998-2012, the empirical model regresses the annual flow of migrants from an origin subdistrict to a destination subdistrict on measures of terror incidents in the origin and the destination, respectively. The results indicate that terror in the destination subdistrict acts as a deterrent to migration into that region, whereas we find no evidence in support of the hypothesis that terror brings about outmigration