Spatially resolved quantum plasmon modes in metallic nano-films from first principles

Electron energy loss spectroscopy (EELS) can be used to probe plasmon excitations in nanostructured materials with atomic-scale spatial resolution. For structures smaller than a few nanometers quantum effects are expected to be important, limiting the validity of widely used semi-classical response models. Here we present a method to identify and compute spatially resolved plasmon modes from first principles based on a spectral analysis of the dynamical dielectric function. As an example we calculate the plasmon modes of 0.5-4 nm thick Na films and find that they can be classified as (conventional) surface modes, sub-surface modes, and a discrete set of bulk modes resembling standing waves across the film. We find clear effects of both quantum confinement and non-local response. The quantum plasmon modes provide an intuitive picture of collective excitations of confined electron systems and offer a clear interpretation of spatially resolved EELS spectra.Comment: 7 pages, 7 figure

Plasmons on the edge of MoS2 nanostructures

Using ab initio calculations we predict the existence of one-dimensional (1D), atomically confined plasmons at the edges of a zigzag MoS2 nanoribbon. The strongest plasmon originates from a metallic edge state localized on the sulfur dimers decorating the Mo edge of the ribbon. A detailed analysis of the dielectric function reveals that the observed deviations from the ideal 1D plasmon behavior result from single-particle transitions between the metallic edge state and the valence and conduction bands of the MoS2 sheet. The Mo and S edges of the ribbon are clearly distinguishable in calculated spatially resolved electron energy loss spectrum owing to the different plasmonic properties of the two edges. The edge plasmons could potentially be utilized for tuning the photocatalytic activity of MoS2 nanoparticles

Responsible corporate governance: An overview of trends, initiatives and state-of-the-art elements. What sort of globalisation is sustainable?

Transnational corporations' (TNCs) economic operations cover numerous countriesand can be diverted between several continents. These units have reached a level ofsignificance, having not only economic, but also social and environmental implications. This justifies that they shall be treated separately as a social phenomenon,when considering strategies for the development towards sustainability.This paper presents the concept of Responsible Corporate Governance (RCG), asa strategy to govern TNCs. RCG is suggested as a stakeholder based policyinstrument, which aims at allocating responsibilities to societal actors aiming atcorporate accountability. RCG recognises that the process of societal change isstrongly based on what can be called as bottom up-processes. Learning processestake place through the interaction of the different societal members, whicheventually leads to macro changes. Therefore, governing TNCs towards sustainability improvements is considered to be a collective process including all stakeholders. Firstly, the paper places the concept of RCG in the ongoing debateof political modernization based on the fact that society develops overtime and thepolitical system must correspondingly modernize. In this context, politicaloverload developed as a consequence of increased resource interdependencies isexplained and as a resolution, network approach is discussed. Secondly, demands on the orientation of the TNCs in terms of accountability and innovative actionare brought forward. Here, the paper also lists down corporate elements (stakeholder empowered corporate governance, management and performanceevaluation systems, transparency enhancement and accountability verification), which need to be in place to attain an accountable orientation in the society.Following, using an analytical framework, the orientation and capabilities of each societal actor (environmental non-governmental organisations, financial institutions, intergovernmental organisations) to affect improvements in the corporateresponsibility elements are investigated and recommendations for their effectiveorientation are listed. --

Discovering new two-dimensional topological insulators from computational screening

We have performed a computational screening of topological two-dimensional (2D) materials from the Computational 2D Materials Database (C2DB) employing density functional theory. A full \textit{ab initio} scheme for calculating hybrid Wannier functions directly from the Kohn-Sham orbitals has been implemented and the method was used to extract $\mathbb{Z}_2$ indices, Chern numbers and Mirror Chern numbers of 3331 2D systems including both experimentally known and hypothetical 2D materials. We have found a total of 46 quantum spin Hall insulators, 7 quantum anomalous Hall insulators and 9 crystalline topological insulators that are all predicted to be dynamically stable. Roughly one third of these were known prior to the screening. The most interesting of the novel topological insulators are investigated in more detail. We show that the calculated topological indices of the quantum anomalous Hall insulators are highly sensitive to the approximation used for the exchange-correlation functional and reliable predictions of the topological properties of these materials thus require methods beyond density functional theory. We also performed $GW$ calculations, which yield a gap of 0.65 eV for the quantum spin Hall insulator PdSe$_2$ in the MoS$_2$ crystal structure. This is significantly higher than any known 2D topological insulator and three times larger than the Kohn-Sham gap.Comment: 12 page

Fish farm ecology : a conceptual framework and empirical investigation of the CSR performance of Marine Harvest ASA and Cermaq ASA

The purpose of this master thesis is to give business participants, regulatory authorities, researchers and the broader community awareness of priority areas within the fish farming industry. In this sense, we have developed a conceptual framework; Fish Farm Ecology (FFE). The FFE model equates three spheres; economy, ecology, and ichthyology. It has flexibility and can be used both as an analytical tool for a broader interest group and as a management tool for companies within the industry. The conceptual framework and the empirical investigation are based upon five context areas; fish feed, sea cages, escaping, sea lice, and the slaughter process. In the empirical investigation, which is concentrated around two companies; Marine Harvest ASA and Cermaq ASA, perspectives of CSR and ethics are included. The CSR-FFE performance of Marine Harvest lies within the upper edge of a minor link, while Cermaq’s lies within the intermediate link

Visualizing hybridized quantum plasmons in coupled nanowires:From classical to tunneling regime

We present full quantum mechanical calculations of the hybridized plasmon modes of two nanowires at small separation, providing real space visualization of the modes in the transition from the classical to the quantum tunneling regime. The plasmon modes are obtained as certain eigenfunctions of the dynamical dielectric function which is computed using time dependent density functional theory (TDDFT). For freestanding wires, the energy of both surface and bulk plasmon modes deviate from the classical result for low wire radii and high momentum transfer due to effects of electron spill-out, non-local response, and coupling to single-particle transitions. For the wire dimer the shape of the hybridized plasmon modes are continuously altered with decreasing separation, and below 6 {\AA} the energy dispersion of the modes deviate from classical results due to the onset of weak tunneling. Below 2-3 {\AA} separation this mode is replaced by a charge-transfer plasmon which blue shifts with decreasing separation in agreement with experiment, and marks the onset of the strong tunneling regime.Comment: To appear in PR

Sustainable Development and Collective Learning: Theory and a European Case Study. Bruges European Economic Policy (BEEP) Briefing 7/2004

Network governance of collective learning processes is an essential approach to sustainable development. The first section of the article briefly refers to recent theories about both market and government failures that express scepticism about the way framework conditions for market actors are set. For this reason, the development of networks for collective learning processes seems advantageous if new solutions are to be developed in policy areas concerned with long-term changes and a stepwise internalisation of externalities. With regard to corporate actors’ interests, the article shows recent insights from theories about the knowledge-based firm, where the creation of new knowledge is based on the absorption of societal views. This concept shifts the focus towards knowledge generation as an essential element in the evolution of sustainable markets. This involves at the same time the development of new policies. In this context innovation-inducing regulation is suggested and discussed. The evolution of the Swedish, German and Dutch wind turbine industries are analysed based on the approach of governance put forward in this article. We conclude that these coevolutionary mechanisms may take for granted some of the stabilising and orientating functions previously exercised by basic regulatory activities of the state. In this context, the main function of the governments is to facilitate learning processes that depart from the government functions suggested by welfare economics