832 research outputs found
Electronic structure and dimerization of a single monatomic gold wire
The electronic structure of a single monatomic gold wire is presented for the
first time. It has been obtained with state-of-the-art ab-initio full-potential
density-functional (DFT) LMTO (linearized muffin-tin orbital) calculations
taking into account relativistic effects. For stretched structures in the
experimentally accessible range the conduction band is exactly half-filled,
whereas the band structures are more complex for the optimized structure. By
studying the total energy as a function of unit-cell length and of a possible
bond-length alternation we find that the system can lower its total energy by
letting the bond lengths alternate leading to a structure containing separated
dimers with bond lengths of about 2.5 \AA, largely independent of the
stretching. However, first for fairly large unit cells (above roughly 7 \AA),
is the total-energy gain upon this dimerization comparable with the energy
costs upon stretching. We propose that this together with band-structure
effects is the reason for the larger interatomic distances observed in recent
experiments. We find also that although spin-orbit couplings lead to
significant effects on the band structure, the overall conclusions are not
altered, and that finite Au_2, Au_4, and Au_6 chains possess electronic
properties very similar to those of the infinite chain.Comment: (14 pages, 5 figures; Elsevier Preprint style elsart.sty
Political Islam and Europe - Views from the Arab Mediterranean states and Turkey. CEPS Working Document, No. 264, 10 April 2007
The social, political and economic power of moderate Middle East and North African Islamist movements has been growing for a generation or so. The question of how to deal with Islamists who reject violence, embrace democracy and outperform their competitors at the polls has therefore become a central concern not only of incumbent Middle East elites, but also of interested foreign actors such as the EU and US. Robert Springborg sees the need for the EU to clarify its policies towards the MENA region and Muslim democrats within it. The present lack of EU policies on engaging with moderate Islamists leads them to be at best curious about the EU and at worse to be suspicious of it. Engagement might itself help to contribute to policy formation in this important area, and serve as a vehicle to disseminate information about relevant EU policies
Non-universality of commonly used correlation-energy density functionals
The correlation energies of the helium isoelectronic sequence and of Hooke's
atom isoelectronic sequence have been evaluated using an assortment of local,
gradient and meta-gradient density functionals. The results are compared with
the exact correlation energies, showing that while several of the more recent
density functionals reproduce the exact correlation energies of the helium
isoelectronic sequence rather closely, none is satisfactory for Hooke's atom
isoelectronic sequence. It is argued that the uniformly acceptable results for
the helium sequence can be explained through simple scaling arguments that do
not hold for Hooke's atom sequence, so that the latter system provides a more
sensitive testing ground for approximate density functionals. This state of
affairs calls for further effort towards formulating correlation-energy density
functionals that would be truly universal at least for spherically-symmetric
two-fermion systems.Comment: To appear in J. Chem. Phy
Structural and electronic properties of Si/Ge nanoparticles
Results of a theoretical study of the electronic properties of (Si)Ge and
(Ge)Si core/shell nanoparticles, homogeneous SiGe clusters, and GeSi
clusters with an interphase separating the Si and Ge atoms are presented. In
general, (Si)Ge particles are more stable than (Ge)Si ones, and SiGe systems
are more stable than GeSi ones. It is found that the frontier orbitals, that
dictate the optical properties, are localized to the surface, meaning that
saturating dangling bonds on the surface with ligands may influence the optical
properties significantly. In the central parts we identify a weak tendency for
the Si atoms to accept electrons, whereas Ge atoms donate electrons.Comment: To appear in Phys. Rev.
Arts-based methods for facilitating meta-level learning in management education: Making and expressing refined perceptual distinctions
Arts-based methods are increasingly used to facilitate meta-level learning in management education. Such increased use suggests that these methods are relevant and offer a unique contribution meeting a need in todayâs management education. Yet, the literature is not clear on what this unique contribution may be even though it abounds with suggestions of varying quality. To explore this matter, I conduct a systematic literature review focused on arts-based methods, management education, and meta-level learning. I find that the unique contribution of arts-based methods is to foreground the process of making and expressing more refined perceptual distinctions, not to get accurate data, but as integral to our thinking/learning. This finding is important, because it imply that certain (commonly applied) ways of using arts-based methods may limit their potential. Finally, I suggest that future research regarding arts-based methods should focus on exploring the impact the process of learning to make and express more refined perceptual distinctions may have on managerial practice to further understand the relevance of these methods to managers
Thomas Hobbes and the Political Economy of Peace
Thomas Hobbesâs theory of war is currently being re-examined as part of a re-examination of realism in international relations theory which claims to be Hobbes-based. I am not alone in maintaining that Hobbes was first and foremost a peace theorist, rejecting the usual grounds for war, pretexts based on just war, infringements on property or trade, and thus trespass. But those who examine the three-fold causes of war that Hobbes gives, as âcompetitionâ, âdiffidenceâ, and âgloryâ, have generally not noticed the relation between Hobbesâs theory of war and empire. While Hobbes makes remarkably few references to the colonial ventures of Great Britain, for reasons that we will consider, his theory of empire, like his theory of war, is based on classical notions of internal balance and the homeostasis of the body politic along Aristotelian lines. His treatment of the polity as a natural body is consistent with his materialist ontology and he treats war and empire in terms of both âintestine diseasesâ and pathologies that afflict the body politic from without. The upshot is a theory remarkably backward-looking in terms of its emphasis on the health of the body politic and the politics of balance, which forbid âvain-glorious warsâ and demand that overly-powerful subjects, towns of âimmoderate greatnessâ and grandiose enlargements of dominion be excised, like Aristotleâs âbig footâ whose disproportion spoils the proportion of the body as a whole
Volume 2: Development Models in Muslim Contexts : Chinese, \u27Islamic\u27 and Neo-liberal Alternatives
Recent discussions of the \u27Chinese economic development model\u27, the emergence of an alternative \u27Muslim model\u27 over the past quarter century and the faltering globalisation of the \u27Washington Consensus\u27 all point to the need to investigate more systematically the nature of these models and their competitive attractions.
This is especially the case in the Muslim world which both spans different economic and geographic categories and is itself the progenitor of a development model.
The \u27Chinese model\u27 has attracted the greatest attention in step with that country\u27s phenomenal growth and therefore provides the primary focus for this book. This volume examines the characteristics of this model and its reception in two major regions of the world - Africa and Latin America.
It also investigates the current competition over development models across Muslim contexts. The question of which model or models, if any, will guide development in Muslim majority countries is vital not only for them, but for the world as a whole. This is the first political economy study to address this vital question as well as the closely related issue of the centrality of governance to development.https://ecommons.aku.edu/uk_ismc_series_emc/1003/thumbnail.jp
- âŠ