Parallel, linear-scaling building-block and embedding method based on localized orbitals and orbital-specific basis sets

We present a new linear scaling method for the energy minimization step of semiempirical and first-principles Hartree-Fock and Kohn-Sham calculations. It is based on the self-consistent calculation of the optimum localized orbitals of any localization method of choice and on the use of orbital-specific basis sets. The full set of localized orbitals of a large molecule is seen as an orbital mosaic where each tessera is made of only a few of them. The orbital tesserae are computed out of a set of embedded cluster pseudoeigenvalue coupled equations which are solved in a building-block self-consistent fashion. In each iteration, the embedded cluster equations are solved independently of each other and, as a result, the method is parallel at a high level of the calculation. In addition to full system calculations, the method enables to perform simpler, much less demanding embedded cluster calculations, where only a fraction of the localized molecular orbitals are variational while the rest are frozen, taking advantage of the transferability of the localized orbitals of a given localization method between similar molecules. Monitoring single point energy calculations of large poly(ethylene oxide) molecules and three dimensional carbon monoxide clusters using an extended Huckel Hamiltonian are presented.Comment: latex, 15 pages, 10 figures, accepted for publication in J.Chem.Phy

Origins and Resolution of a Banking Crisis: Chile 1982-86

Starting in 1981, Chile went into a deep economic and financial crisis. The Chilean solution to the crisis was heterodox in the sense that many policies appear to have been arbitrary, and policy mistakes were made and corrected along the way. However, the economy recovered relatively quickly, and since has built a strong financial sector that allowed the country to avoid the financial turmoil observed during 1995 and 1997-98 in other emerging market economies. This paper reviews and evaluates the Chilean experience of the early 1980s. In particular, it discusses the macroeconomic internal and external environment that led to the banking crisis, and describes in detail the main measures implemented to its resolution. The paper attempts to identify which policies worked and which ones did not. To the extent allowed by the data, we try to see how (and which of) the different policies led to a recovery of the solvency in the banking system.

Direct evidence of intervalence charge-transfer states of Eu-doped luminescent materials

Direct evidence is given for the existence of intervalence charge transfer (IVCT) states of Eu2+/Eu3+ pairs in Eu-doped CaF2 , SrF2, and BaF2 . They are detected in diffuse reflectance spectra. In doped materials, IVCT states, in which an electron transfer occurs between two metal sites differing only in oxidation state, are rather difficult to observe because the absorption bands are extremely broad and flat, their intensity is low, and no emission follows the IVCT absorptions. Their assignment as IVCT states is provided by state-of-the-art multiconfigurational ab initio calculations. Although IVCT states of lanthanide-doped materials have largely been overlooked so far, they can cause luminescence quenching and even complete luminescence excitation loss. Their direct observation and independent assignment in classical dopant (Eu) and hosts (CaF2, SrF2, BaF2) are very significant: They suggest that the occurrence of IVCT states in other lanthanide-activated materials is very likely overlooked and their impact is ignored

El paleolítico y el epipaleolítico. Arqueología de Vasconia Peninsular

Se evalúan los datos recuperados en los últimos años sobre esta etapa en Vasconia Peninsular. El conocimiento que hoy se tiene de ella ha experimentado un notable progreso: dedicándose varias excavaciones a épocas hasta ahora no demasiado bien conocidas (p.e. el primer tercio del Paleolítico superior o el Mesolítico) y aplicando a su interpretación una metodología interdisciplinar (con estudios cruzados de tecnotipología, estratigrafía y aprovechamiento del medio....). Se llama la atención sobre las dificultades de financiación y apoyo institucional que parecen amenazar próximamente el desarrollo de esta líneas de investigación.Garai horri buruz azken urteetan bilduriko datuak ebaluatzen dira. Gaur egun hartaz dugun ezagupenak aurrerabide handia egin du: gaur arte oso ondo ezagutzen ez ziren garaiei dagozkien indusketa batzuk burutu dira (adibidez, Goi Paleolitos Aroaren lehen herena edo Mesolitos aroa) eta haien interpretazioan disziplinarteko metodologia aplikatu dira (teknotipologia, estratigrafia eta ngurunearen aprobetxamenduaren gaineko azterketak). Finantziako eta erkundeen aldeko laguntzaren inguruko zailtasunez ohartarazten da, antza denez horren eskasiek etorkizun hurbilean ikerketa-lerroen garapena mehatxatzen baitu.On évalue les données recueillies au cours des dermiéres années sur cette étape. La connaissance que nous en avons aujourd'hui a expérimenté un progrés notable: en déciant plusieurs excavations à des époques jusqu'alors peu connues (p.e. le premier tiers du paléolithique supérieur ou le Mésolithique) et en appliquant une méthodologie interdisciplinaire (avec études croisées de technotypologie, stratigraphie et utilisation de l'environnement,...) à son interprétation . On fait remarquer les difficultés de financement et d'appui institutionnei qui semblent menacer prochainement le dévelopement de ces lignes de recherche

Haudenosaunee: Los principios indígenas de la democracia

El presente trabajo expone de forma sucita el consenso estudioso y público que hoy reconoce la originalidad y relevancia del sistema de convivencia y co-gobierno que un conglomerado de naciones indígenas consolidó en el contorno tierras continentales. El Artículo examina el peculiar influjo que el modelo de la "Liga Iroquesa" llegó a ejercer sobre las habidas mentes que, luego del triunfo de las 13 colonias sobre el imperio británico en 1776, necesitarían imaginar un nuevo concepto de integración sociopolític

Gaurgaraiko logika edo logistika

Se comparan diferentes tipos de lógicas de manera que se pueden ver las diferencias entre ellasDifferent types of logics are compaired so as to see the differences they have between the