Vibrational anharmonicity of small gold and silver clusters using the VSCF method

We study the vibrational spectra of small neutral gold (Au2–Au10) and silver (Ag2–Au5) clusters using the vibrational self-consistent field method (VSCF) in order to account for anharmonicity. We report harmonic, VSCF, and correlation-corrected VSCF calculations obtained using a vibrational configuration interaction approach (VSCF/VCI). Our implementation of the method is based on an efficient calculation of the potential energy surfaces (PES), using periodic density functional theory (DFT) with a plane-wave pseudopotential basis. In some cases, we use an efficient technique (fast-VSCF) assisted by the Voter–Chen potential in order to get an efficient reduction of the number of pair-couplings between modes. This allows us to efficiently reduce the computing time of 2D-PES without degrading the accuracy. We found that anharmonicity of the gold clusters is very small with maximum rms deviations of about 1 cm−1, although for some particular modes anharmonicity reaches values slightly larger than 2 cm−1. Silver clusters show slightly larger anharmonicity. In both cases, large differences between calculated and experimental vibrational frequencies (when available) stem more likely from the quality of the electronic structure method used than from vibrational anharmonicity. We show that noble gas embedding often affects the vibrational properties of these clusters more than anharmonicity, and discuss our results in the context of experimental studies

The nature and role of the gold-krypton interactions in small neutral gold clusters

© 2015 American Chemical Society. We investigate the nature and role of krypton embedding in small neutral gold clusters. For some of these clusters, we observe a particular site-dependent character of the Kr binding that does not completely follow the criterion of binding at low-coordinated sites, widely accepted for interaction of a noble gas with closed-shell metal systems such as metal surfaces. We aim at understanding the effect of low dimensionality and open-shell electronic structure of the odd-numbered clusters on the noble gas-metal cluster interaction. First, we investigate the role of attractive and repulsive forces, and the frontier molecular orbitals. Second, we investigate the Au-Kr interaction in terms of reactivity and bonding character. We use a reactivity index derived from Fukui formalism, and criteria provided by the electron localization function (ELF), in order to classify the type of bonding. We carry out this study on the minimum energy structures of neutral gold clusters, as obtained using pseudo potential plane-wave density functional theory (DFT). A model is proposed that includes the effect of attractive electrostatic, van der Waals and repulsive forces, together with effects originating from orbital overlap. This satisfactorily explains minimum configurations of the noble gas-gold cluster systems, the site preference of the noble gas atoms, and changes in electronic properties

An alternative methodology to assess the quality of empirical potentials for small gold clusters

We present a methodology based on local comparisons of potential energy surfaces (PES) in order to assess the quality of empirical potentials. We compare five typical empirical potentials using a criterion that shows which of these potentials resembles better a PES obtained with a high-level electronic structure method. The methodology relies on a many-body expansion in terms of normal coordinates of both the empirical and high-level theory PES. Then we investigate in a systematical way, how the features of the reference high-level theory PES are reproduced by each empirical potential in the vicinity of a given minimum energy structure. We use plane-wave density functional theory (DFT) as a reference, in particular the Perdew–Burke–Ernzerhof (PBE) exchange–correlation functional and an ultrasoft Vanderbilt pseudo potential. This study is carried out on neutral gold clusters with up to five atoms

Testimonios sobre el teatro en Caracas: crisis y transformaciones en el siglo XXI

The problematization of the evolution of performing arts has decreased in current theatrical research. This may be due to some level of fear regarding today's cultural situation, or to the present reality of Caracas, which shows the impact of political events, of the mass media, and of the lack of a permanent criticism devoted to the theatrical scene. This essay seeks to make visible Caracas' theatrical creations in an analysis of the theater within the cultural context of the capital city during the 21st Century, based on a set of interviews with emerging and established artists, and highlighting aesthetic and cultural conjuncturesEn las actuales investigaciones teatrales ha disminuido la problematización sobre el devenir del arte escénico, ya sea por temor a la situación cultural de hoy o por una Caracas sacudida por el acontecer político, los medios de comunicación masivos, y la falta de permanente crítica para el seguimiento de la práctica teatral. Este ensayo se propone visibilizar las creaciones teatrales caraqueñas en un análisis del teatro dentro del contexto sociocultural de la ciudad capital durante el siglo XXI, sustentado en un conjunto de entrevistas realizadas a creadores emergentes y consolidados, poniendo en evidencia las coyunturas estéticas y culturales

Direct Electron Transfer of Human Hemoglobin Molecules on Glass/Tin-Doped Indium Oxide

Interfacial electron transfer kinetics of the haem (FeIII/FeII) group in human hemoglobin molecules were investigated on glass/tin-doped indium oxide electrodes. Factors such as surface roughness, crystallinity, hydrophilicity and partial polarization of the working electrode played an important role to provide a more compatible microenvironment for protein adsorption. Results suggested that direct electron transfer from electrode to haem (FeIII)-H2O intermediate is coupled to proton at near physiological pH (I = 0.035, pH = 7.2)

Sistematizacion de los procesos de PYL Compuservicios S.A.S

P&L COMPUSERVICIOS S.A.S. es una empresa del sector tecnológico, dedicado a brindar servicio de mantenimiento y reparación de equipos de cómputo. Es una organización que cuenta con más de 20 años de existencia que ha decidido sistematizar sus procesos mediante la creación de un sistema informático que permita llevar el control y estado de estos procesos, mejorarlos y así brindar mayor comodidad, confianza y satisfacción a sus clientes. En el campo de la ingeniería de sistemas existen programas que ofrecen desarrollo gratuito de aplicaciones, herramientas con almacenamiento en la nube, almacenamiento local y brindan un entorno agradable y de fácil manejo por parte del usuario final, es por ello por lo que se tomó la determinación de invertir en tecnología, implementando tal sistema, para el beneficio de los empleados y clientes de la empresa. Así mismo se trazó como objetivo diseñar, desarrollar y realizar pruebas funcionales de un software que permita llevar el control de un inventario, ingreso y egreso de equipos a mantenimiento o reparación, facturación y venta de artículos o servicios de la empresa

Environmental Sustainability in the Public Services Company of Sogamoso S.A. ESP. In the period 2013-2014

The contamination of rivers, lagoons, dams and other wastewater bodies has become a major concern due to its impact on the quality of life of the population and the development of economic activities that require the use of water of such bodies. This concern has led to the emergence of an administrative legal framework for regulating this problem, which, in turn, has stimulated the growth of investments in environmental sanitation projects. Considering that the use of these resources means a high opportunity cost, it is very important to raise the quality of such investments through the improvement of their social profitabilityThe contamination of rivers, lagoons, dams and other wastewater bodies has become a major concern due to its impact on the quality of life of the population and the development of economic activities that require the use of water of such bodies. This concern has led to the emergence of an administrative legal framework for regulating this problem, which, in turn, has stimulated the growth of investments in environmental sanitation projects. Considering that the use of these resources means a high opportunity cost, it is very important to raise the quality of such investments through the improvement of their social profitabilit

Modificación de actitudes en las comunidades de pueblo nuevo y la población indígena achagua del resguardo umapo, municipio de Puerto López - Meta

Imágenes, GráficasA 30 kilómetros del municipio de Puerto Gaitán (Meta) se encuentra ubicada la comunidad indígena Achagua con una antigüedad de asentamiento más o menos de 50 años, hace aproximadamente 10 años, los colonos provenientes de distintas regiones del país invadieron el territorio de la comunidad y fundaron un nuevo caserío con el nombre de Pueblo Nuevo, ocupando territorio que pertenece a la comunidad indígena. La influencia colonizadora que ha generado la explotación del petróleo en los campos de Rubiales, en el municipio de Puerto Gaitán en el departamento del Meta, los colonizadores provienen de diferentes partes del país, en busca de oportunidades para mejorar su calidad de vida, una proporción de esta población abandona su territorio debido a problemas de desplazamiento forzado, de orden público, es la causa principal del fenómeno del desplazamiento forzado y la explotación de los recursos naturales, (petróleo), pone en riesgo y vulnera los derechos fundamentales de una persona o grupo, en cualquier situación o condición. La modificación de actitudes en las comunidades de pueblo nuevo y la población indígena Achagua del resguardo la Umapo, municipio de puerto López – Meta, que tienden a generar conflictos y luchas por el reconocimiento social y un análisis del interés y la diversidad cultural. La aplicación de la Psicología Social comunitaria, busca dar un aporte en la solución de problemas y el acercamiento de la universidad a la sociedad en general. Es importante indicar que la comunicación entre las dos comunidades de Pueblo Nuevo y los indígenas Achagua, presenta la no aceptación del dialecto, ni las costumbres, mitos y creencias; es decir no se refleja integración, solidaridad y cooperación. Por ello, hay presencia de rivalidad entre ellas.To 30 kilometres of the municipality of Port Gaitán (Put) there is located the indigenous community Achagua by an antiquity of accession more or less of 50 years, approximately 10 years ago, the colonists from different regions of the country invaded the territory of the community and founded a new hamlet with the name of New People, occupying territory that belongs to the indigenous community

Propuesta para la creación de un fondo de capital de riesgo para la Universidad Pedagógica y Tecnológica de Colombia sede Sogamoso

In this article the results of the market research and progress of the research project for the creation of a venture capital fund for the Pedagogical and Technological University of Colombia at Sogamoso. Made by the research group attached to the program management business administration. Allowing leverage and university spin-off research projects and innovative database technology originating in research projects conducted by faculty, students and graduates of the seat.En el presente  artículo se abordan los resultados del estudio de investigación de mercados como avance del proyecto de investigación para la creación de un fondo de capital de riesgo para la Universidad Pedagógica y Tecnológica de Colombia sede Sogamoso. Realizado por el grupo de investigación management adscrito al programa de administración de empresas. Que permita apalancar los spin-off universitarios y proyectos de investigación de base tecnológica e innovadores que se originen en los proyectos de investigación realizados por docentes, estudiantes y egresados de la sede