Effective atomic orbitals for fuzzy atoms

The method of extracting effective atomic orbitals and effective minimal basis sets from molecular wave function characterizing the state of an atom in a molecule is developed in the framework of the "fuzzy" atoms. In all cases studied, there were as many effective orbitals that have considerable occupation numbers as orbitals in the classical minimal basis. That is considered to be of high conceptual importance

One- and two-center energy components in the atoms in molecules theory

The energy decomposition scheme proposed in a recent paper has been realized by performing numerical integrations. The sample calculations carried out for some simple molecules show excellent agreement with the chemical picture of molecules, indicating that such an energy decomposition analysis can be useful from the point of view of connecting quantum mechanics with the genuine chemical concepts

Energy partitioning for "fuzzy" atoms

The total energy of molecule in terms of 'fuzzy atoms' presented as sum of one- and two-atomic energy components is described. The divisions of three-dimensional physical space into atomic regions exhibit continuous transition from one to another. The energy components are on chemical energy scale according to proper definitions. The Becke's integration scheme and weight function determines realization of method which permits effective numerical integrations

Un Món que creix

Aquesta entrega d’Engega comença amb un resum a grans trets de l’evolució de la implantació dels graus a la UdG, un dels reptes més importants de la docència en els últims anys

Generació Einstein 3.0. La comunicació en un món nou

Imaginem-nos que volem vendre alguna cosa a un jove: un producte, una idea o potser unes pràctiques a la nostra empresa. Com ho faríeu? Quins mètodes podríeu fer servir? Ho faríeu de la mateixa manera que ho heu fet sempre? Penseu que els vostres anuncis, textos publicitaris, llocs web o cartells encara serien vàlids? Creieu que tots els diners invertits en comunicació i màrqueting us ajudarien a assolir l’objectiu? Si la resposta a aquestes preguntes és que sí, aleshores no cal que continueu llegint. Podeu continuar comunicant-vos amb els joves com ho heu fet fins ara, perquè us funciona. Però si us passa com a tots nosaltres i reconeixeu que la comunicació amb els joves no és tan fàcil, que de vegades us sembla que no us veuen o no us senten, aleshores us convidem a continuar llegint. No pretenem oferir totes les respostes, ja que no tenim la clau dels seus cors, però sí que volem mirar d’entendre el seu comportament, la seva manera de pensar i les seves accions

La Relació entre el món laboral i el món de l'educació en persones amb discapacitat

La fundació Síndrome de Down de Girona i Comarques Astrid – 21 és una fundació privada benèfica de tipus assistencial. La finalitat dels seus programes és la protecció de les persones amb síndrome de Down al llarg de la seva vida, però també està oberta a altres discapacitats intel•lectuals. Aquest treball se centra en el programa “formació d’adults” que ofereix una formació a totes aquelles persones amb discapacitat que ja estan inserides en el món laboral. L’estudi que he dut a terme sorgeix d’una problemàtica latent en aquest programa. Els grups, en un principi, estaven formats per persones amb un nivell cognitiu més o menys semblant. Tot i això, degut a la incorporació de nous alumnes, la coordinació amb l’horari laboral i amb activitats de lleure, entre d’altres factors, ha provocat l’heterogeneïtat d’aquests. Per aquest motiu, a partir del paradigma d’investigació – acció, he creat uns instruments de mesura de les capacitats cognitives dels alumnes relacionades amb els objectius treballats al programa per tal de reelaborar els grups ja existents i, al mateix temps, tenir una eina per a futures incorporacions del programa “formació d’adults” de la Fundació Astrid 21

El Món funerari antic, tardoantic i altomedieval a la ciutat de Girona: u n estat de la qüestió

Article que estudia els cementiris antics i altomedievals de la ciutat de Girona ubicats a l'entorn immediat de la ciutat, a la riba esquerra del riu Onyar i intra muros

Ab initio and tight-binding calculations of noncollinear magnetism in manganese clusters

Combining ab initio and tight-binding calculations, we have studied the noncollinear magnetism in manganese clusters. The oscillations in the per-atom moments observed experimentally are reproduced theoretically. The tendency of antiferromagnetic coupling between near neighbors leads to noncollinear coupling between atoms within the clusters. For clusters containing 12, 13, 15, 19, and 23 atoms, the geometrical structures were optimized from ab initio calculations with collinear coupled spin moments among different atomic sites. For larger clusters such as Mn-36 and Mn-55, the geometries are taken as portions of an fcc structure. Although the local atomic moments have high values close to 4 mu(B), the net moments lie in the range of 0.4-1.2 mu(B)/atom. Taking the noncollinear coupling into account brings the calculated magnetic moments much closer to the experimental results.

Laboratory kinetic studies of the reactions of Cl atoms with species of biogenic origin: δ3-Carene, isoprene, methacrolein and methyl vinyl ketone

The rate coefficients for the reaction between atomic chlorine and a number of naturally occurring species have been measured at ambient temperature and atmospheric pressure using the relative rate technique. The values obtained were (4.0 ± 0.8) × 10-10, (2.1 ± 0.5) × 10-10, (3.2 ± 0.5) × 10-10, and (4.9 ± 0.5) × 10-10 cm3 molecule-1 s-1, for reactions with isoprene, methyl vinyl ketone, methacrolein and δ3-carene, respectively. The value obtained for isoprene compares favourably with previously reported values. No values have been reported to date for the rate constants of the other reactions.

Synthesis, structure and magnetic characterisation of a new layered ammonium manganese(II) diphosphate hydrate, (NH4)(2)[Mn-3(P2O7)(2)(H2O)(2)]

A new layered ammonium manganese(II) diphosphate, (NH4)(2)[Mn-3(P2O7)(2)(H2O)(2)], has been synthesised under solvothermal conditions at 433 K in ethylene glycol and the structure determined at 293 K using single-crystal X-ray diffraction data (M-r = 584.82, monoclinic, space group P2(1)/a, a = 9.4610( 8), b = 8.3565( 7), c = 9.477(1) Angstrom, beta = 99.908(9) degrees, V = 738.07 Angstrom(3), Z = 2, R = 0.0351 and R-w = 0.0411 for 1262 observed data (I > 3(sigma(I))). The structure consists of chains of cis- and trans-edge sharing MnO6 octahedra linked via P2O7 units to form layers of formula [Mn3P4O14(H2O)(2)](2-) in the ab plane. Ammonium ions lie between the manganese-diphosphate layers. A network of interlayer and ammonium-layer based hydrogen bonding holds the structure together. Magnetic measurements indicate Curie - Weiss behaviour above 30 K with mu(eff) = 5.74(1) mu(B) and theta = -23(1) K, consistent with the presence of high-spin Mn2+ ions and antiferromagnetic interactions. However, the magnetic data reveal a spontaneous magnetisation at 5 K, indicating a canting of Mn2+ moments in the antiferromagnetic ground state. On heating (NH4)(2)[Mn-3(P2O7)(2)(H2O)(2)] in water at 433 K under hydrothermal conditions, Mn-5(HPO4)(2)(PO4)(2).4H(2)O, synthetic hureaulite, is formed.

Catena-Poly[bis(ethane-1,2-diammonium) [manganese(II)-di-mu-phosphato-kappa O-4 : O ']]: a one-dimensional manganese phosphate

The title compound,{(C2H10N2)(2)[Mn(PO4)(2)]}(n), contains anionic square-twisted chains of formula [Mn(PO4)(2)](4-) constructed from corner-sharing four-membered rings of alternating MnO4 and PO4 units. The Mn and P atoms have distorted tetrahedral coordination and the Mn atom lies on a twofold axis. The linear manganese-phosphate chains are held together by hydrogen-bonding interactions involving the framework O atoms and the H atoms of the ethane-1,2-diammonium cations, which lie in the interchain spaces.

Structural diversity in supramolecular architectures of Mn(II) through non-covalent interactions

Two mononuclear complexes of manganese(II), [Mn(OCN)(2)(phen)(2)] 1 and [Mn(NCO)(2)(bpy)(2)] 2 [1,10-phenanthroline (phen); 2,2'-bipyridine (bpy)], have been synthesized and characterized by single crystal X-ray analysis, infra-red spectroscopy and magnetic studies. The coordination structure of complex 2 is already reported. The cyanate anions are pendent in both the complexes. In 1, cyanate anion links manganese(II) through O-atom, whereas in 2 it coordinates through N-atom. The mononuclear fragments of 1 are built up to a supramolecular lamellar 3D architecture by pi-pi interactions only. On the other hand, mononuclear fragments of 2 are assembled to a 2D supramolecular brick-wall architecture by C-H-... pi interactions.