1,535 research outputs found
Human Rights and Cultural Diversity. Core Issues and Cases
As clearly explained on the very first page, this book is about “the troubled relationship between the promotion of human rights and the promotion of cultural diversity.” Its purpose is to discuss (and overcome, I presume) some of the “core areas of anxiety” that this trouble speaks of. Anyone working with human rights, academically or in more applied ways, will be familiar with the anxieties that arise from trying to reconcile individual and collective rights in a consistent and convincing manner. A book holding the promise of taking you one step further towards simultaneously handling the issues of individual moral rights and collectivist cultural rights should attract a wide readership
S 2p photoabsorption of the SF5CF3 molecule: Experiment, theory and comparison with SF6
The S 2p core excitation spectrum of the SF5CF3 molecule has been measured in the total ion yield mode. It resembles a lot the analogous spectrum of SF6, also recorded in this study, displaying intense transitions to the empty molecular orbitals both below and above the S 2p ionization potential (IP) and weak transitions to the Rydberg orbitals. The S 2p photoabsorption spectra of SF6 and SF5CF3 have been calculated using time-dependent density functional theory, whereby the spin–orbit coupling was included for the transitions below the S 2p IP. The agreement between experiment and theory is good for both molecules, which allows us to assign the main S 2p absorption features in SF5CF3
Capital of Feedback
The body of work by British architect Cedric Price (1934–2003) is largely concerned with architecture’s relationship to technology and its impact on society. As contemporary architecture finds itself confronted with similar issues today, Price’s designs are being revisited and hailed for their prospective and inventive visions. As such, it seems timely to ask if Price’s designs can be regarded as precedents for future projects that aim to couple participation and technology through architectural design.
In this article, I depart from the economic logic of today’s digital platforms to analyse the participatory elements Cedric Price designed for Oxford Corner House (1965–66) to be ‘self-participatory entertainment’. As user participation has gradually been capitalised on through the evolution of digital technologies, I argue that the conditions for what participatory architecture entails have changed in turn. Whereas Price regarded the transfer of information as an activity for users of the Oxford Corner House to engage with freely, the operation of today’s digital platforms instead suggests that such activities are entirely facilitated in order to retrieve information from its users. In order to make this argument, I look at how Cedric Price envisioned digital technologies to sustain participation and in turn how he understood the concept of user participation and its relation to the architectural programme
Optical absorption of (Ag-Au)133(SCH3)52 bimetallic monolayer-protected clusters
Abstract The evolution of the optical absorption spectrum of bimetallic Ag-Au monolayer-protected clusters (MPC) obtained by progressively doping Ag into the experimentally known structure of Au 133 (SR) 52 was predicted via rigorous time-dependent density-functional theory (TDDFT) calculations. In addition to monometallic Au 133 (SR) 52 and Ag 133 (SR) 52 species, 5 different (Ag-Au) 133 (SR) 52 homotops were considered with varying Ag content and site positioning, and their electronic structure and optical response were analyzed in terms of Projected Density Of States (PDOS), the induced or transition electron density, and Transition Component Maps (TCM) at selected excitation energies. It was found that Ag doping led to the effects rather different from those encountered in bare metal clusters. And it was also observed that Ag doping could produce structured spectral features, especially in the 3–4 eV range but also in the optical region if Ag atoms were located in the sub-staple region, as rationalized by the accompanying electronic analysis. Additionally, Au doping into the staples of Ag-rich MPC also gave rise to a more homogeneous induced electron density. These findings show the great sensitivity of the electronic response of MPC nanoalloy systems to the exact location of the alloying sites
Optimization of density fitting auxiliary Slater-type basis functions for time-dependent density functional theory
A new set of auxiliary basis function suitable to fit the induced electron density is presented. Such set has been optimized in order to furnish accurate absorption spectra using the complex polarizability algorithm of time-dependent density functional theory (TDDFT). An automatic procedure has been set up, able, thanks to the definition of suitable descriptors, to evaluate the resemblance of the auxiliary basis-dependent calculated spectra with respect to a reference. In this way, it has been possible to reduce the size of the basis set maximizing the basis set accuracy. Thanks to the choice to employ a collection of molecules for each element, such basis has proven transferable to molecules outside the collection. The final sets are therefore much more accurate and smaller than the previously optimized ones and have been already included in the database of the last release of the AMS suite of programs. The availability of the present new set will allow to improve drastically the applicability range of the polTDDFT method with higher accuracy and less computational effort
A computational approach for modeling electronic circular dichroism of solvated chromophores
The present study consists in a novel computational protocol to model the UV-circular dichroism spectra of solvated species. It makes use of quantum-chemical calculations on a series of conformations of a flexible chromophore or on a series of chromophore/solvent clusters extracted from molecular dynamic simulations. The protocol is described and applied to the aqueous cationic tripeptide GAG(+) and to the aqueous neutral decapeptide (GVGVP)(2). The protocol has proven able to: (i) properly consider the conformational motion of solute in the given environment; (ii) give the actual statistical weight of each conformational state; (iii) provide a reliable quantum mechanical method able to reproduce the spectral features. Temperature effects on conformations and spectral properties are properly taken into account. The role of explicit solvent on the conformational analysis and the spectra calculation is discussed. The comparison of the calculated circular dichroism spectra with experimental ones recorded at different temperatures represents a strict validation test of the method
Electronic circular dichroism from real-time propagation in state space
In this paper, we propose to compute the electronic circular dichroism (ECD) spectra of chiral molecules using a real-time propagation of the time-dependent Schrodinger equation (TDSE) in the space of electronic field-free eigenstates, by coupling TDSE with a given treatment of the electronic structure of the target. The time-dependent induced magnetic moment is used to compute the ECD spectrum from an explicit electric perturbation. The full matrix representing the transition magnetic moment in the space of electronic states is generated from that among pairs of molecular orbitals. In the present work, we show the ECD spectra of methyloxirane, of several conformers of L-alanine, and of the lambda-Co(acac)(3) complex, computed from a singly excited ansatz of time-dependent density functional theory eigenstates. The time-domain ECD spectra properly reproduce the frequency-domain ones obtained in the linear-response regime and quantitatively agree with the available experimental data. Moreover, the time-domain approach to ECD allows us to naturally go beyond the ground-state rotationally averaged ECD spectrum, which is the standard outcome of the linear-response theory, e.g., by computing the ECD spectra from electronic excited states
Optical Activity of Metal Nanoclusters Deposited on Regular and Doped Oxide Supports from First-Principles Simulations
We report a computational study and analysis of the optical absorption processes of Ag20
and Au20 clusters deposited on the magnesium oxide (100) facet, both regular and including point
defects. Ag20 and Au20 are taken as models of metal nanoparticles and their plasmonic response, MgO
as a model of a simple oxide support. We consider oxide defects both on the oxygen anion framework
(i.e., a neutral oxygen vacancy) and in the magnesium cation framework (i.e., replacing Mg++ with a
transition metal: Cu++ or Co++). We relax the clusters’ geometries via Density-Functional Theory
(DFT) and calculate the photo-absorption spectra via Time-Dependent DFT (TDDFT) simulations
on the relaxed geometries. We find that the substrate/cluster interaction induces a broadening and
a red-shift of the excited states of the clusters, phenomena that are enhanced by the presence of an
oxygen vacancy and its localized excitations. The presence of a transition-metal dopant does not
qualitatively affect the spectral profile. However, when it lies next to an oxygen vacancy for Ag20,
it can strongly enhance th
A new time dependent density functional algorithm for large systems and plasmons in metal clusters
A new algorithm to solve the Time Dependent Density Functional Theory (TDDFT) equations in the
space of the density fitting auxiliary basis set has been developed and implemented. The method
extracts the spectrum from the imaginary part of the polarizability at any given photon energy,
avoiding the bottleneck of Davidson diagonalization. The original idea which made the present
scheme very efficient consists in the simplification of the double sum over occupied-virtual pairs
in the definition of the dielectric susceptibility, allowing an easy calculation of such matrix as a linear
combination of constant matrices with photon energy dependent coefficients. The method has been
applied to very different systems in nature and size (from H2 to [Au147] 12). In all cases, the maximum
deviations found for the excitation energies with respect to the Amsterdam density functional code are
below 0.2 eV. The new algorithm has the merit not only to calculate the spectrum at whichever photon
energy but also to allow a deep analysis of the results, in terms of transition contribution maps, Jacob
plasmon scaling factor, and induced density analysis, which have been all implemente
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