Economic Growth, Inequality, Democratization, and the Environment

We augment the Stokey (1998) model by allowing agents to differ with respect to environmental quality and income in order to analyze the impact of income and environmental inequality, and of democratization on aggregate pollution. We find that the impact of a more equal income distribution depends on the degree of democracy. In a complete democracy a more equal income distribution generates, ceteris paribus, less pollution, which is consistent with indirect empirical evidence, whereas the opposite is the case if democratic rights are highly restricted. Further-more, a democratization is argued to typically lower both the income and the environmental quality of the median voter. In this case, if, in utility terms, the fall in environmental quality is worse than the fall in consumption the median voter decides to tighten environmental legislation so that aggregate pollution decreases.Economic growth and the environment; inequality; politics

Trends in Ferromagnetism in Mn doped dilute III-V alloys from a density functional perspective

Mn doping in dilute III-V alloys has been examined as a route to enhance ferromagnetic stability. Strong valence band bowing is expected at the dilute limit, implying a strong modification of the ferromagnetic stability upon alloying, with even an increase in some cases. Using first principle electronic structure calculations we show that while codoping with a group V anion enhances the ferromagnetic stability in some cases when the effects of relaxation of the lattice are not considered, strong impurity scattering in the relaxed structure result in a reduction of the ferromagnetic stability.Comment: 12 pages, 3 figures, Accepted in Physical Review

Noble gas as a functional dopant in ZnO

Owing to fully occupied orbitals, noble gases are considered to be chemically inert and to have limited effect on materials properties under standard conditions. However, using first-principles calculations, we demonstrate herein that the insertion of noble gas (i.e., He, Ne, or Ar) in ZnO results in local destabilization of electron density of the material driven by minimization of an unfavorable overlap of atomic orbitals of the noble gas and its surrounding atoms. Specifically, the noble gas defect (interstitial or substitutional) in ZnO pushes the electron density of its surrounding atoms away from the defect. Simultaneously, the host material confines the electron density of the noble gas. As a consequence, the interaction of He, Ne, or Ar with O vacancies of ZnO in different charge states q (ZnO:VOq) affects the vacancy stability and their electronic structures. Remarkably, we find that the noble gas is a functional dopant that can delocalize the deep in-gap VOq states and lift electrons associated with the vacancy to the conduction band.Comment: 15 pages, 4 figure

Thermoelectric transport of GaAs, InP, and PbTe: Hybrid functional with k⋅p{\bf \it k \cdot p} interpolation versus scissor-corrected generalized gradient approximation

Boltzmann transport calculations based on band structures generated with density functional theory (DFT) are often used in the discovery and analysis of thermoelectric materials. In standard implementations, such calculations require dense ${\it k}$-point sampling of the Brillouin zone and are therefore typically limited to the generalized gradient approximation (GGA), whereas more accurate methods such as hybrid functionals would have been preferable. GGA variants, however, generally underestimate the band gap. While premature onset of minority carriers can be avoided with scissor corrections, the band gap also affects the band curvature. In this study, we resolved the ${\it k}$-point sampling issue in hybrid-functional based calculations by extending our recently developed ${\it k}\cdot\tilde{{\it p}}$ interpolation scheme [Comput. Mater. Sci. 134, 17 (2017)] to non-local one-electron potentials and spin-orbit coupling. The Seebeck coefficient generated based on hybrid functionals were found to agree better than GGA with experimental data for GaAs, InP, and PbTe. For PbTe, even the choice of hybrid functional has bearing on the interpretation of experimental data, which we attribute to the description of valley convergence of the valence band.Comment: 8 pages, 9 figure

Изучение факторов венозного возврата на основе физико-математической модели венозной гемодинамики нижних конечностей в норме

КРОВОТОКА СКОРОСТЬГЕМОДИНАМИКИ ФЕНОМЕНЫКОНЕЧНОСТЬ НИЖНЯЯВЕНЫКОМПЬЮТЕРНОЕ МОДЕЛИРОВАНИ

Lithium atom storage in nanoporous cellulose via surface induced Li2\rm Li_2 breakage

We demonstrate a physical mechanism that enhances a splitting of diatomic $\rm Li_2$ at cellulose surfaces. The origin of this splitting is a possible surface induced diatomic excited state resonance repulsion. The atomic Li is then free to form either physical or chemical bonds with the cellulose surface and even diffuse into the cellulose layer structure. This allows for an enhanced storage capacity of atomic Li in nanoporous celluloseComment: 5 pages, 6 figure

Optical properties of Cu2ZnSn(SxSe1-x)4 by first-principles calculations

Structural, electronic and optical properties of Cu2ZnSn(SxSe1-x)4 semiconductors are studied theoretically for different concentration of S and Se anions. The optical properties are calculated at three levels of theory, in the generalized gradient approximation (GGA), meta-GGA, and with a hybrid functional. The GGA and meta-GGA calculations are corrected with an on-site Coulomb Ud term. Lattice constants, dielectric constants, and band-gaps are found to vary almost linearly with the concentration of S. We also show that a dense sampling of the Brillouin zone is required to accurately account for the shape of the dielectric function, which is hard to attain with hybrid functionals. This issue is resolved with a recently developed k dot p based interpolation scheme, which allows us to compare results of the hybrid functional calculations on an equal footing with the GGA and meta-GGA results. We find that the hybrid functionals provide the overall best agreement with the experimental dielectric function

Tailoring electronic properties of multilayer phosphorene by siliconization

Controlling a thickness dependence of electronic properties for two-dimensional (2d) materials is among primary goals for their large-scale applications. Herein, employing a first-principles computational approach, we predict that Si interaction with multilayer phosphorene (2d-P) can result in the formation of highly stable 2d-SiP and 2d-SiP$_2$ compounds with a weak interlayer interaction. Our analysis demonstrates that these systems are semiconductors with band gap energies that can be governed by varying the thickness and stacking order. Specifically, siliconization of phosphorene allows to design 2d-SiP$_x$ materials with significantly weaker thickness dependence of electronic properties than that in 2d-P and to develop ways for their tailoring. We also reveal the spatial dependence of electronic properties for 2d-SiP$_x$ highlighting difference in effective band gaps for different layers. Particularly, our results show that central layers in the multilayer 2d systems determine overall electronic properties, while the role of the outermost layers is noticeably smaller