The nature of the Cr-C bond: direct estimation of aromaticity in Fischer carbenes

Report for the scientific sojourn at the the Philipps-Universität Marburg, Germany, from september to december 2007. For the first, we employed the Energy-Decomposition Analysis (EDA) to investigate aromaticity on Fischer carbenes as it is related through all the reaction mechanisms studied in my PhD thesis. This powerful tool, compared with other well-known aromaticity indices in the literature like NICS, is useful not only for quantitative results but also to measure the degree of conjugation or hyperconjugation in molecules. Our results showed for the annelated benzenoid systems studied here, that electron density is more concentrated on the outer rings than in the central one. The strain-induced bond localization plays a major role as a driven force to keep the more substituted ring as the less aromatic. The discussion presented in this work was contrasted at different levels of theory to calibrate the method and ensure the consistency of our results. We think these conclusions can also be extended to arene chemistry for explaining aromaticity and regioselectivity reactions found in those systems.In the second work, we have employed the Turbomole program package and density-functionals of the best performance in the state of art, to explore reaction mechanisms in the noble gas chemistry. Particularly, we were interested in compounds of the form H--Ng--Ng--F (where Ng (Noble Gas) = Ar, Kr and Xe) and we investigated the relative stability of these species. Our quantum chemical calculations predict that the dixenon compound HXeXeF has an activation barrier for decomposition of 11 kcal/mol which should be large enough to identify the molecule in a low-temperature matrix. The other noble gases present lower activation barriers and therefore are more labile and difficult to be observable systems experimentally.

Web per a psicologia i teràpia online Espai Nirvana

Aquest Treball de Final de Carrera engloba l'anàlisi, el disseny i la implementació d'una aplicació web per a psicologia i teràpia online. L'enginyeria d'aquest programari està basada en la tècnica d'orientació a objectes, dins l'estàndard UML. Els aspectes generals de l'anàlisi i disseny s'han desenvolupat amb un cicle de vida en cascada, per tenir una bona base de partida i poder confeccionar una planificació en el temps. La fase de implementació, està basada en un cicle de vida iteratiu e incremental, implementant a cada iteració una petita part amb autonomia que correspon a un cas d'ús. Com a llenguatge de desenvolupament he escollit Java , i com a arquitectura de l'aplicació J2EE, degut a la seva robustesa i a que en l'actualitat, té un fort posicionament en aplicacions web i en xarxa, arribant a ser un estàndard en l'entorn distribuït d'aplicacions empresarials a Internet. En l'estratègia en el disseny i per donar solucions efectives a problemes tipificats, he fet servir el patró MVC, que a més, ha incrementat considerablement la reusabilitat i efectivitat del codi i estructura de la programació. Per a la implementació he incorporat el framework Struts2, que basa la seva arquitectura en el patró MVC, i que ha facilitat molt el treball ja que ha donat solucions a problemes generals estàndard i altres de baix nivell, i ha permès focalitzar els esforços en donar solució a qüestions més particulars i específiques del projecte. En l'accés transparent a les dades he optat per Hibernate3, una poderosa eina que enllaça el món relacional de les BBDD amb el mon de l'orientació a objectes de les classes de les aplicacions. I com a SGBD per a la persistència de dades, he fet servir Oracle 10g XE, també tot un referent en la indústria, i un dels més complets.

Delocalization and fragmentation of collective modes in doped 4He drops

We have investigated the fragmentation of collective modes in doped 4He drops in the framework of a finite-range density-functional theory, as well as the delocalization of the impurity inside the cluster. Our results indicate that the impurity is gradually delocalized inside the drop as the size of the latter increases. As an example, results are shown in the case of Xe-4HeN systems up to N=112.

Pinning of quantized vortices in helium drops by dopant atoms and molecules

Using a density functional method, we investigate the properties of liquid 4He droplets doped with atoms (Ne and Xe) and molecules ( SF6 and hydrogen cyanide). We consider the case of droplets having a quantized vortex pinned to the dopant. A liquid-drop formula is proposed that accurately describes the total energy of the complex and allows one to extrapolate the density functional results to large N. For a given impurity, we find that the formation of a dopant+vortex+4HeN complex is energetically favored below a critical size Ncr. Our results support the possibility to observe quantized vortices in helium droplets by means of spectroscopic techniques.

Quantized vortices in mixed 3He-4He drops

Using density functional theory, we investigate the structure of mixed 3HeN3-4HeN4 droplets with an embedded impurity (Xe atom or HCN molecule) which pins a quantized vortex line. We find that the dopant+vortex+4HeN4 complex, which in a previous work [F. Dalfovo et al., Phys. Rev. Lett. 85, 1028 (2000)] was found to be energetically stable below a critical size Ncr, is robust against the addition of 3He. While 3He atoms are distributed along the vortex line and on the surface of the 4He drop, the impurity is mostly coated by 4He atoms. Results for N4 = 500 and a number of 3He atoms ranging from 0 to 100 are presented, and the binding energy of the dopant to the vortex line is determined.

Disseny i implementació d'un clúster high performance computing

Clúster format per una màquina principal HEAD Node més 19 nodes de càlcul de la gama SGI13 Altix14 XE Servers and Clusters, unides en una topologia de màster subordinat, amb un total de 40 processadors Dual Core i aproximadament 160Gb de RAM.