651 resultados para Funcions de densitat
Resumo:
Es descriu la figura de la mestra assessora, creada al CEIP Margalida Florit de Ciutadella. La mestra assessora t?? una visi?? transversal del projecte d'escola i s'encarrega d???assessorar, guiar i animar el projecte d???aula durant tot el seu proc??s mitjan??ant reunions peri??diques amb la resta de l???equip educatiu. En primer lloc, es fa una breu contextualitzaci?? del centre i es comenta el tipus de model educatiu que necessita. Seguidament, s???exposen les principals funcions que corresponen al perfil professional de la mestra assessora. Finalment, es comenten els aspectes positius a l???hora de comptar amb aquesta figura professional dins del centre educatiu.
Resumo:
A l’article que presento pareix que l’Administració educativa fos la culpable de certes concepcions errònies dels docents, i en part és així. Per exemple, l’Administració manté creences que han desaparegut per considerar la investigació que en són inadequades. Entre les noves funcions fomentades per l’investigació educativa i que no es posen mai en funcionament es citen: els estils cognitius que apareixen a mitjans dels seixanta, la modificabilitat cognitiva amb unes pautes d’actuació molt estrictes a l’hora d’aplicar els instruments que les desenvolupen i en conseqüència es divideix al màxim el problema a resoldre. La conversació exploratòria i amb ella, la presència del llibre de text (com a tal) desapareix i dona lloc al llibre de consulta i la comprensió lectora que sense els elements abans esmentats no es dona i és el centre de tot l’aprenentatge. La proposta que present a l’article té un repte: les mesures dels exercicis són més complexes (no paramètriques) i no es poden reflectir tan fàcilment.
Resumo:
En un moment en que Catalunya i, sobretot, la regió metropolitana de Barcelona, experimenta un procés d'ocupació del territori sense precedents, es especialment important avançar en l'estudi dels possibles connectors existents, el seu reconeixement i la seva delimitació en el planejament territorial, El 13 de juliol de 2004 es va signar i fer públic el Manifest de Sant Celoni pel reconeixement de les vies verdes del Vallès. En aquest manifest es demana, entre altres mesures, el reconeixement i la delimitació en el planejament territorial de 7 grans vies verdes: Obac-Olorda, Sant Llorenç-Collserola, Farell-Marina, Gallifa-Gallecs, Tagamanent-Cellecs, Calma-Corredor, Montseny-Montnegre. Totes aquestes vies exerceixen funcions de connexió ecològica i paisatgística entre les serralades Litoral i Prelitoral i, juntament amb altres espais menys urbanitzats que hi ha al peu de la serralada Prelitoral, integren el sistema d'espais oberts del Vallès. Aquesta ponència presenta, en primer lloc, el marc conceptual on s'inscriu el concepte via verda. En segon lloc, explica els principals antecedents en relació amb les vies verdes del Vallès que apareixen en el Manifest de Sant Celoni, i, finalment l’encaix de les vies verdes del Vallès en el planejament territorial de la regió metropolitana de Barcelona, així com les principals línies estratègiques que es podrien seguir per convertir-les en una realitat
Resumo:
Anàlisi de funcionament del Centre d’Atenció i Seguiment de drogodependents (CAS) Teresa Ferrer), i posterior proposta de viabilitat per incorporar la figura del/de la psicopedagog/a en un centre com aquest. Es busca un suport legal que ho recolzi, i es fa una exposició de totes les funcions que podria assolir aquest nou professional, incloent-hi les que actualment ja es duen a terme i altres que es podrien realitzar
Resumo:
La docència és una de les principals funcions de la universitat. Se situa just al costat de la recerca, amb la qual forma un conjunt simbiòtic que cal entendre com a tal en el desenvolupament de l’una i de l’altra. A la Universitat de Girona s’entén que l’exercici de la docència és responsabilitat del professorat, que, amb la seva expertesa i la seva professionalitat, busca en tot moment la millor manera d’aconseguir bons aprenentatges per als estudiants. Tot i això, la UdG, especialment arran de la creació de l’espai europeu d’educació superior, s’ha dotat d’un conjunt de definicions, procediments i eines de suport per al personal docent que, a més de facilitar la docència, els proporciona un segell propi, sempre amb el respecte a la iniciativa docent del professorat. Aquest quadern és la presentació d’aquestes definicions, procediments i eines, alhora que vol ser una breu guia de la UdG per al professorat que hi entra a treballar de bell nou
Resumo:
Bimodal dispersal probability distributions with characteristic distances differing by several orders of magnitude have been derived and favorably compared to observations by Nathan [Nature (London) 418, 409 (2002)]. For such bimodal kernels, we show that two-dimensional molecular dynamics computer simulations are unable to yield accurate front speeds. Analytically, the usual continuous-space random walks (CSRWs) are applied to two dimensions. We also introduce discrete-space random walks and use them to check the CSRW results (because of the inefficiency of the numerical simulations). The physical results reported are shown to predict front speeds high enough to possibly explain Reid's paradox of rapid tree migration. We also show that, for a time-ordered evolution equation, fronts are always slower in two dimensions than in one dimension and that this difference is important both for unimodal and for bimodal kernels
Resumo:
A select-divide-and-conquer variational method to approximate configuration interaction (CI) is presented. Given an orthonormal set made up of occupied orbitals (Hartree-Fock or similar) and suitable correlation orbitals (natural or localized orbitals), a large N-electron target space S is split into subspaces S0,S1,S2,...,SR. S0, of dimension d0, contains all configurations K with attributes (energy contributions, etc.) above thresholds T0={T0egy, T0etc.}; the CI coefficients in S0 remain always free to vary. S1 accommodates KS with attributes above T1≤T0. An eigenproblem of dimension d0+d1 for S0+S 1 is solved first, after which the last d1 rows and columns are contracted into a single row and column, thus freezing the last d1 CI coefficients hereinafter. The process is repeated with successive Sj(j≥2) chosen so that corresponding CI matrices fit random access memory (RAM). Davidson's eigensolver is used R times. The final energy eigenvalue (lowest or excited one) is always above the corresponding exact eigenvalue in S. Threshold values {Tj;j=0, 1, 2,...,R} regulate accuracy; for large-dimensional S, high accuracy requires S 0+S1 to be solved outside RAM. From there on, however, usually a few Davidson iterations in RAM are needed for each step, so that Hamiltonian matrix-element evaluation becomes rate determining. One μhartree accuracy is achieved for an eigenproblem of order 24 × 106, involving 1.2 × 1012 nonzero matrix elements, and 8.4×109 Slater determinants
Resumo:
Linear response functions are implemented for a vibrational configuration interaction state allowing accurate analytical calculations of pure vibrational contributions to dynamical polarizabilities. Sample calculations are presented for the pure vibrational contributions to the polarizabilities of water and formaldehyde. We discuss the convergence of the results with respect to various details of the vibrational wave function description as well as the potential and property surfaces. We also analyze the frequency dependence of the linear response function and the effect of accounting phenomenologically for the finite lifetime of the excited vibrational states. Finally, we compare the analytical response approach to a sum-over-states approach
Resumo:
The contributions of the correlated and uncorrelated components of the electron-pair density to atomic and molecular intracule I(r) and extracule E(R) densities and its Laplacian functions ∇2I(r) and ∇2E(R) are analyzed at the Hartree-Fock (HF) and configuration interaction (CI) levels of theory. The topologies of the uncorrelated components of these functions can be rationalized in terms of the corresponding one-electron densities. In contrast, by analyzing the correlated components of I(r) and E(R), namely, IC(r) and EC(R), the effect of electron Fermi and Coulomb correlation can be assessed at the HF and CI levels of theory. Moreover, the contribution of Coulomb correlation can be isolated by means of difference maps between IC(r) and EC(R) distributions calculated at the two levels of theory. As application examples, the He, Ne, and Ar atomic series, the C2-2, N2, O2+2 molecular series, and the C2H4 molecule have been investigated. For these atoms and molecules, it is found that Fermi correlation accounts for the main characteristics of IC(r) and EC(R), with Coulomb correlation increasing slightly the locality of these functions at the CI level of theory. Furthermore, IC(r), EC(R), and the associated Laplacian functions, reveal the short-ranged nature and high isotropy of Fermi and Coulomb correlation in atoms and molecules
Resumo:
A topological analysis of intracule and extracule densities and their Laplacians computed within the Hartree-Fock approximation is presented. The analysis of the density distributions reveals that among all possible electron-electron interactions in atoms and between atoms in molecules only very few are located rigorously as local maxima. In contrast, they are clearly identified as local minima in the topology of Laplacian maps. The conceptually different interpretation of intracule and extracule maps is also discussed in detail. An application example to the C2H2, C2H4, and C2H6 series of molecules is presented
Resumo:
The electron localization function (ELF) has been proven so far a valuable tool to determine the location of electron pairs. Because of that, the ELF has been widely used to understand the nature of the chemical bonding and to discuss the mechanism of chemical reactions. Up to now, most applications of the ELF have been performed with monodeterminantal methods and only few attempts to calculate this function for correlated wave functions have been carried out. Here, a formulation of ELF valid for mono- and multiconfigurational wave functions is given and compared with previous recently reported approaches. The method described does not require the use of the homogeneous electron gas to define the ELF, at variance with the ELF definition given by Becke. The effect of the electron correlation in the ELF, introduced by means of configuration interaction with singles and doubles calculations, is discussed in the light of the results derived from a set of atomic and molecular systems
Resumo:
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
Resumo:
The performance of the SAOP potential for the calculation of NMR chemical shifts was evaluated. SAOP results show considerable improvement with respect to previous potentials, like VWN or BP86, at least for the carbon, nitrogen, oxygen, and fluorine chemical shifts. Furthermore, a few NMR calculations carried out on third period atoms (S, P, and Cl) improved when using the SAOP potential
Resumo:
A comparision of the local effects of the basis set superposition error (BSSE) on the electron densities and energy components of three representative H-bonded complexes was carried out. The electron densities were obtained with Hartee-Fock and density functional theory versions of the chemical Hamiltonian approach (CHA) methodology. It was shown that the effects of the BSSE were common for all complexes studied. The electron density difference maps and the chemical energy component analysis (CECA) analysis confirmed that the local effects of the BSSE were different when diffuse functions were present in the calculations
Resumo:
The effect of basis set superposition error (BSSE) on molecular complexes is analyzed. The BSSE causes artificial delocalizations which modify the first order electron density. The mechanism of this effect is assessed for the hydrogen fluoride dimer with several basis sets. The BSSE-corrected first-order electron density is obtained using the chemical Hamiltonian approach versions of the Roothaan and Kohn-Sham equations. The corrected densities are compared to uncorrected densities based on the charge density critical points. Contour difference maps between BSSE-corrected and uncorrected densities on the molecular plane are also plotted to gain insight into the effects of BSSE correction on the electron density