2,523 research outputs found
2− molecules: Some insights from wave function theory
No full textThe aim of this paper is to unravel the physical phenomena involved in the calculation of the spin density of the CuCl2 and [CuCl4]2− systems using wave function methods. Various types of wave functions are used here, both variational and perturbative, to analyse the effects impacting the spin density. It is found that the spin density on the chlorine ligands strongly depends on the mixing between two types of valence bond structures. It is demonstrated that the main difficulties found in most of the previous studies based on wave function methods come from the fact that each valence bond structure requires a different set of molecular orbitals and that using a unique set of molecular orbitals in a variational procedure leads to the removal of one of them from the wave function. Starting from these results, a method to compute the spin density at a reasonable computational cost is proposed
Spin density and orbital optimization in open shell systems: A rational and computationally efficient proposal
No full textThe present work describes a new method to compute accurate spin densities for open shell systems. The proposed approach follows two steps: first, it provides molecular orbitals which correctly take into account the spin delocalization; second, a proper CI treatment allows to account for the spin polarization effect while keeping a restricted formalism and avoiding spin contamination. The main idea of the optimization procedure is based on the orbital relaxation of the various charge transfer determinants responsible for the spin delocalization. The algorithm is tested and compared to other existing methods on a series of organic and inorganic open shell systems. The results reported here show that the new approach (almost black-box) provides accurate spin densities at a reasonable computational cost making it suitable for a systematic study of open shell systems
Emmanuel Kutik
No full textabstract: Emmanuel Kutik was almost eight years old when he left his home. He walked for three months and traveled with fifty people.
“Lost Boys Found” is an ongoing, interdisciplinary project that is collecting, recording and archiving the oral histories of the Lost Boys/Girls of Sudan. The collection is a work-in-progress, seeking to record the oral history of as many Lost Boys/Girls as are willing, and will be used in a future book.Age: 23Region: BentiuThis picture and bio was donated to the Lost Boys Found project from The Arizona Lost Boys Cente
Conflitto sociale e decisione pubblica nell’era digitale : il Grand Débat National nella Francia di Macron
No full textAl fine di arginare l’ondata di proteste che ha investito la Francia a partire dal settembre 2018, il Presidente della Repubblica, Emmanuel Macron, nel dicembre 2018, ha annunciato lo svolgimento di una consultazione a livello nazionale, il Grand Débat National o GDN. Tale nuovo strumento, ideato per rispondere ad un bisogno di partecipazione nell’ambito di una grave crisi di consenso, presenta innegabili elementi di novità legati al contesto nel quale è stato introdotto ed all’ampiezza dei temi affrontati, pur inserendosi nella consolidata tradizione giuspubblicistica francese del débat public
Honorable Emmanuel Okocha Oral History Interview
No full textThis is an oral history interview with the Honorable Emmanuel Okocha, author of Blood on the Niger, the only book about the Asaba Massacre, a mass killing of civilians which occurred in 1967 during the Nigerian Civil War. Okocha, a survivor of the massacre, was a small child at the time; his father was killed at Asaba, and two older brothers also died during the war. Okocha began researching the massacre after finishing his university studies, and has interviewed hundreds of survivors and relatives of those who were killed. He describes some of his research, the publication of his book, and his efforts to document the massacre
Emmanuel Cooper OBE 1938–2012 A Retrospective Exhibition
No full textDr Emmanuel Cooper OBE (HonDFA) 1938–2012 was a distinguished craftsman, writer, teacher and broadcaster. A potter of international standing, his work is represented in many public collections. The author of nearly thirty books, he was editor of Ceramic Review, visiting Professor at London’s Royal College of Art, and a regular broadcaster on television and radio. He was awarded an OBE in 2002 for services to art. Emmanuel’s contribution to the world of ceramics was hugely significant. This will be celebrated with a touring exhibition of his ceramics and a publication looking at his life in pots – produced by Ruthin Craft Centre in collaboration with the University of Derby
Entanglement and Mutual Information in Molecules: Comparing Localized and Delocalized Orbitals
No full textThe use of the mutual information (MI) as a measure of the entanglement in quantum systems has gained a consensus in recent years, even if there is an ongoing effort to distinguish the classical and quantum contributions contained therein. This quantity has been first introduced in condensed matter physics, in particular, in studies based on the density matrix renormalization group method. This method has been successfully adapted to quantum chemistry problems, opening the way to compute MI also in molecular systems. A key aspect of this quantity is its dependence on the one-electron (orbital) basis set, even for wave functions that are invariant under unitary transformation of the orbitals. In this work, we investigate the role of the orbital basis set (delocalized or localized, following different strategies) for wave functions expressed as linear combinations of Slater determinants and we give the analytic expression for the MI for a few special cases. This study aims to improve the knowledge of the relationship between the characteristics of the chemical bond (considering a few paradigmatic molecules, H2, F2, N2, and short linear polyenes) and the properties of interest in the field of quantum information theory
Immobile History: An Interview with Emmanuel Le Roy Ladurie
No full textThe author spoke with renowned French historian Emmanuel Le Roy Ladurie about Computers, Geography and History. Le Roy Ladurie was the "standard bearer" of the third generation of the French Annales school, a group of French intellectuals that combined different disciplines such as history, geography, anthropology, and more to delve into social history
Emmanuel B. Dongala
No full textA chapter on Congolese writer Emmanuel B. Dongala in the Dictionary of Literary Biography. (Vol. 360: Contemporary Arican Writers). --author-supplied descriptio
Ouvrages en débat. La démocratie des chimères. Gouverner la biologie synthétiqueSara Angeli Aguiton Bord de l’eau, 2018, 247 p
No full textInternational audienceLe Bord de l'eau, 2018, 247 p. Le livre de Sara Angeli Aguiton (CNRS, Centre Alexandre-Koyré) s'adresse tout particulièrement à ceux qui s'intéressent aux biotechnologies et à leur impact sur la société
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