University of Vienna

About: University of Vienna is a education organization based out in Vienna, Austria. It is known for research contribution in the topics: Population & Context (language use). The organization has 44686 authors who have published 95840 publications receiving 2907492 citations.

Cu 2 ZnSnS 4 as a potential photovoltaic material: A hybrid Hartree-Fock density functional theory study

Abstract: First-principles calculations for the potential photovoltaic material ${\text{Cu}}_{2}{\text{ZnSnS}}_{4}$ (CZTS) are presented using density functional theory and the Perdew-Burke-Ernzerhof exchange-correlation functional as well as using the Heyd-Scuseria-Ernzerhof (HSE) hybrid functional. The HSE results compare very favorably to experimental data for the lattice constants and the band gap, as demonstrated for CZTS and selected ternary chalcopyrites such as ${\text{CuInS}}_{2}$, ${\text{CuInSe}}_{2}$, ${\text{CuGaS}}_{2}$, and ${\text{CuGaSe}}_{2}$. Furthermore the HSE band structure is validated using ${G}_{0}{W}_{0}$ quasiparticle calculations. The valence band is found to be made up by an antibonding linear combination of $\text{Cu-}3d$ states and $\text{S-}3p$ states, whereas an isolated band made up by $\text{Sn-}5s$ and $\text{S-}3p$ states dominates the conduction band. In the visible wavelength, the optical properties are determined by transitions from the $\text{Cu-}3d/\text{S-}3p$ states into this conduction band. Comparison of the optical spectra calculated in the independent-particle approximation and using time-dependent hybrid functional theory indicates very small excitonic effects. For the structural properties, the kesterite-type structure of $I\overline{4}$ symmetry is predicted to be the most stable one, possibly along with cation disorder within the Cu-Zn layer. The energy differences between structural modifications are well approximated by a simple ionic model.

Combining high biodiversity with high yields in tropical agroforests

Abstract: Local and landscape-scale agricultural intensification is a major driver of global biodiversity loss. Controversially discussed solutions include wildlife-friendly farming or combining high-intensity farming with land-sparing for nature. Here, we integrate biodiversity and crop productivity data for smallholder cacao in Indonesia to exemplify for tropical agroforests that there is little relationship between yield and biodiversity under current management, opening substantial opportunities for wildlife-friendly management. Species richness of trees, fungi, invertebrates, and vertebrates did not decrease with yield. Moderate shade, adequate labor, and input level can be combined with a complex habitat structure to provide high biodiversity as well as high yields. Although livelihood impacts are held up as a major obstacle for wildlife-friendly farming in the tropics, our results suggest that in some situations, agroforests can be designed to optimize both biodiversity and crop production benefits without adding pressure to convert natural habitat to farmland.

National Labour Relations in Internationalized Markets: A Comparative Study of Institutions, Change, and Performance

Abstract: Presents and examines evidence and theories about changing patterns of industrial relations and their links to convergence on the one hand, and economic competitiveness on the other. Includes a comprehensive set of comparable date on industrial relations in twenty OECD countries including Australia, the United States, Canada, Japan, and most leading European countries.