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## Computation of (3)J(HH) coupling constants with a combination of density functional theory and semiempirical calculations. Application to complex molecules

Richter, Wagner E.; Pontes, Rodrigo M.; Abiko, Layara A.; Gauze, Gisele F.; Basso, Ernani A.
Fonte: ELSEVIER SCIENCE BV; AMSTERDAM Publicador: ELSEVIER SCIENCE BV; AMSTERDAM
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.34%
This work evaluates the efficiency of economic levels of theory for the prediction of (3)J(HH) spin-spin coupling constants, to be used when robust electronic structure methods are prohibitive. To that purpose, DFT methods like mPW1PW91. B3LYP and PBEPBE were used to obtain coupling constants for a test set whose coupling constants are well known. Satisfactory results were obtained in most of cases, with the mPW1PW91/6-31G(d,p)//B3LYP/6-31G(d,p) leading the set. In a second step. B3LYP was replaced by the semiempirical methods PM6 and RM1 in the geometry optimizations. Coupling constants calculated with these latter structures were at least as good as the ones obtained by pure DFT methods. This is a promising result, because some of the main objectives of computational chemistry - low computational cost and time, allied to high performance and precision - were attained together. (C) 2012 Elsevier B.V. All rights reserved.; Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES); Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

## Determinação e analise das constantes de acoplamento nJch (n=2,3,4) em derivados do norbornano; Determination and analysis of nJch (n=2,3,4) coupling constants in norbornane derivatives

Francisco Paulo dos Santos
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Relevância na Pesquisa
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A tese está estruturada da seguinte forma. Primeiro uma parte introdutória relatando o efeito das interações hiperconjugativas na constante de acoplamento JXY e uma discussao sobre a as principais metodologias para a determinação de constantes de acoplamento a JXY a longa distância. Nesta primeira parte o leitor e introduzido nos tópicos básicos desta tese. Seguindo o corpo da tese contém os resultados e discussão. Primeiro apresentamos as metodologias para determinação das constantes de acoplamento JCH com enfase para o experimento de HSQMBC e para os experimentos de estado de spin seletivo (HSQC-TOCSY-IPAP e HSQC-TOCSY-IPAP-triplamente editado). Posteriormente apresentamos uma racionalização para a diferença entre os acoplamentos JC4H1 e JC1H4 da 3-exo-2-norbornanona (X = Cl, Br, SCH3). Mostramos que ambos os acoplamentos JC1H e JC4H14 deveriam apresentar uma redução de seus valores, devido as interações hiperconjugativas sC1-C7p*C2=O e sC1-C7s*C2=O que retiram densidade eletrônica do caminho a três ligações. Entretanto, observamos que a existência de uma terceira interação sC3-C4s*C2-O recupera parte da densidade eletrônica do acoplamento JC4H1 através de um caminho adicional a quatro ligações fazendo com que o acoplamento JC4H1 seja maior. Este caminho a quatro ligações é similar ao observado em sistemas homoalílicos...

## Determinação e análise da influência angular e eletrônica nas constantes de acoplamento nJCH em 2-X-4-t-butilcicloexanonas e 2-X-4-t-butilcicloexanóis (X=H, Me, F, Cl, Br); Determination of NMR nJCH spin-spin coupling constants and analysis of their angular and electronic dependence in 2-X-4-t-butylcycloexanonas and 2-X-4-t-butylcycloexanols (X=H, Me, F, Cl, Br)

Denize Cristina Favaro
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
56.28%
A dissertação consiste de uma parte introdutória que versa sobre constantes de acoplamento JXH que seguem ou não uma relação de estrita dependência com o ângulo diedro, proposta por Karplus para JHH e por Aydin e Günther para JCH; apresentando como as interações hiperconjugativas afetam os valores das mesmas. Seguindo a estrutura da dissertação temos os resultados e discussão. Primeiro apresentamos a metodologia de HSQC-TOCSY-IPAP utilizada para determinação das constantes de acoplamento JCH. Posteriormente apresentamos uma racionalização para a diferença entre os acoplamentos JC2H6e para as cetonas cis/trans-2-X-4-t-butilcicloexanonas (X = H, Me, F, Cl e Br) e entre os alcoóis derivados. Mostramos, também, qual a influência do ângulo de ligação C2-C1-C6 na constante de acoplamento JC2H6e onde observamos que para a maioria dos compostos o valor de JC2H6e possui uma relação inversa com esse ângulo interno. Além disso, analisou-se o efeito das interações hiperconjugativas sC1-C6s*C2-Br, LP2(O)s*C1-C2 e LP3(X)s*C1-C2, onde as duas primeiras interações tornam mais efetiva a transmissão do acoplamento e a última retira densidade eletrônica do caminho a três ligações. Por fim, observamos a aplicabilidade das regras propostas por Marshall...

## Analise conformacional por ressonância magnética nuclear e cálculos teóricos em anéis de cinco membros : 2-Halociclopentanonas; Nuclear magnetic resonance and theoretical investigation on the conformational analysis of five-membered ring systems : 2-Halocyclopentanones

Carina Rabelo Martins
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
46.24%

## Computation of (3)J(HH) coupling constants with a combination of density functional theory and semiempirical calculations. Application to complex molecules

Richter, Wagner E.; Pontes, Rodrigo M.; Abiko, Layara A.; Gauze, Gisele F.; Basso, Ernani A.
Fonte: Elsevier; Amsterdam Publicador: Elsevier; Amsterdam
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
66.34%
This work evaluates the efficiency of economic levels of theory for the prediction of (3)J(HH) spin-spin coupling constants, to be used when robust electronic structure methods are prohibitive. To that purpose, DFT methods like mPW1PW91. B3LYP and PBEPBE were used to obtain coupling constants for a test set whose coupling constants are well known. Satisfactory results were obtained in most of cases, with the mPW1PW91/6-31G(d,p)//B3LYP/6-31G(d,p) leading the set. In a second step. B3LYP was replaced by the semiempirical methods PM6 and RM1 in the geometry optimizations. Coupling constants calculated with these latter structures were at least as good as the ones obtained by pure DFT methods. This is a promising result, because some of the main objectives of computational chemistry - low computational cost and time, allied to high performance and precision - were attained together. (C) 2012 Elsevier B.V. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

## Coupling constants of D*DsK and Ds*DK processes

Bracco,M. E.; Lozéa,A.; Cerqueira Jr.,A.; Chiapparini,M.; Nielsen,M.
Tipo: Artigo de Revista Científica Formato: text/html
Relevância na Pesquisa
66.15%
We calculate the coupling constants of D*Ds K and Ds*DK vertices using the QCD sum rules technique. We compare our results with results obtained in the limit of SU(4) symmetry and we found that the symmetry is broken at the order of 40%.

## Estudo experimental de teórico das constantes de acoplamento n ANTPOT. ('J IND. ch') (n= 1,2,3) em adamantanos substituídos; Experimental and theoretical study of n ANTPOT. ('J IND. ch') (n= 1,2,3) spin-spin coupling constants in substituted adamantane

Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
66.39%

## Interações de orbitais e seus efeitos nos acoplamentos 'J SOB.2. J IND H' e 'J SOB.1 J IND CH' em 1, 3, 5-trioxano, 1, 3, 5-tritianos monosubstituidos : um estudo teorico e experimental; Orbital interactions and their effects on 'J SOB.2. J IND H' and 'J SOB.1 J IND CH' coupling constants in 1, 3, 5-trioxane, 1, 3, 5- trithiane and 2-substituted- 1, 3, 5 - trithianes : experimental and theoretical study

Janaina Dantas Vilcachagua
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Relevância na Pesquisa
66.41%
Estudaram-se as interações de orbitais e seus efeitos nas constantes de acoplamento JHH e JCH em 1,3,5-trioxano, 1,3,5-tritiano e 1,3,5-tritianos monosubstituídos, onde os substituintes foram os halogênios: flúor, cloro, bromo e metil por dados de ressonância magnética nuclear e cálculos teóricos. Todos os cálculos foram realizados com os programas GAUSSIAN 98 e 03. Os cálculos de otimização de geometrias foram realizados em nível MP2 e a função de base aug-cc-pVTZ. Os cálculos para estudo das interações hiperconjugativas foram feitos com o programa NBO. As constantes de acoplamento foram calculadas utilizando a teoria de perturbação CP-DFT. Obtiveram-se os espectros de RMN de H e de C a temperatura ambiente e a baixa temperatura para obtenção dos valores das constantes de acoplamentos experimentais. A análise conjunta dos dados teóricos e experimentais para o 1,3,5-trioxano e 1,3,5-tritiano mostrou a influência das interações hiperconjugativas nxs*C-HEq, nxs*C-HAx, e nxs*C-X, onde o X pode ser o átomo de oxigênio ou enxofre, nos valores das constantes de acoplamento JCHax, JCHeq e JHH. A análise conjunta dos dados teóricos e experimentais para 1,3,5-tritianos monosubstituídos mostrou a influência dos átomos eletronegativos...

## Symmetry breakdown and coupling constants of leptons

Marques,Gil C.; Spehler,Dominique
Tipo: Artigo de Revista Científica Formato: text/html
Relevância na Pesquisa
66.15%
Based on a new approach to symmetries of the fundamental interactions we deal, in this paper, with the electroweak interactions of leptons. We show that the coupling constants, arising in the way leptons are coupled to intermediate bosons, can be understood as parameters associated to the breakdown of SU(2) and parity symmetries. The breakdown of both symmetries is characterized by a new parameter (the asymetry parameter) of the electroweak interactions. This parameter gives a measure of the strength of breakdown of symmetries. We analyse the behaviour of the theory for three values of this parameter. The most relevant value is the one for which only the electromagnetic interactions do not break parity (the maximally allowed left-right asymetric theory). Maximamally allowed parity asymmetry is a requirement that is met for a value of Weinberg's theta-angle that is quite close to the experimental value of this parameter.

## The electronic origin of unusually large nJFN coupling constants in some Fluoroximes

Favaro, Denize C.; Contreras, Ruben Horacio; Tormena, Claudio F.
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
66.3%
SOPPA(CCSD) calculations show that the FC term is the most important contribution to the through-space transmission of JFN coupling constants for the fluoroximes studied in this work. Because of the well-known behavior of FC term, a new rationalization for the experimental TSJFN SSCC is presented. It is mainly based on the overlap matrix (Sij) between fluorine and nitrogen lone pairs obtained from NBO analyses. An expression is proposed to take into account the influence of the electronic density (Dij) between coupled nuclei as well as the s% character at the site of the coupling nuclei of bonds and non-bonding electron pairs involved in Dij. In using this approach, a linear correlation between TSJFN versus Dij is obtained. The most important aspect of this rationalization is related to the facility for understanding the behavior of some unusual experimental coupling constants. It is shown that, at least in this case, the electronic origin of the so-called through-space coupling is transmitted through to the overlap of orbitals on the coupled atoms, suggesting that, at least for these compounds, instead of through-space coupling, it should better be dubbed as ‘through overlapping orbital coupling’.; Fil: Favaro, Denize C.. Universidad de Campinas. Instituto de Química; Brasil;; Fil: Contreras...

## Computational NMR coupling constants: Shifting and scaling factors for evaluating 1-J(CH)

San Fabián, J.; García de la Vega, J. M.; Suardíaz, R.; Fernandez Oliva, M.; Pérez, C.; Crespo Otero, R.; Contreras, Ruben Horacio
Tipo: info:eu-repo/semantics/article; info:ar-repo/semantics/artículo; info:eu-repo/semantics/publishedVersion Formato: application/pdf
ENG
Relevância na Pesquisa
66.32%
Optimized shifting and/or scaling factors for calculating one-bond carbon–hydrogen spin–spin coupling constants have been determined for 35 combinations of representative functionals (PBE, B3LYP, B3P86, B97-2 and M06-L) and basis sets (TZVP, HIIIsu3, EPR-III, aug-cc-pVTZ-J, ccJ-pVDZ, ccJ-pVTZ, ccJ-pVQZ, pcJ-2 and pcJ-3) using 68 organic molecular systems with 88 1JCH couplings including different types of hybridized carbon atoms. Density functional theory assessment for the determination of 1JCH coupling constants is examined, comparing the computed and experimental values. The use of shifting constants for obtaining the calculated coupling improves substantially the results, and most models become qualitatively similar. Thus, for the whole set of couplings and for all approaches excluding those using the M06 functional, the root-mean-square deviations lie between 4.7 and 16.4 Hz and are reduced to 4–6.5 Hz when shifting constants are considered. Alternatively, when a specific rovibrational contribution of 5 Hz is subtracted from the experimental values, good results are obtained with PBE, B3P86 and B97-2 functionals in combination with HIII-su3, aug-cc-pVTZ-J and pcJ-2 basis sets.; Fil: San Fabián, J.. Universidad Autónoma de Madrid. Facultad de Ciencias. Departamento de Química Física Aplicada; España;; Fil: García de la Vega...

## Renormalization Group Invariant Constraints among Coupling Constants in a Noncommutative Geometry Model

Umezawa, Eizou
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.24%
We study constraints among coupling constants of the standard model obtained in the noncommutative geometry (NCG) method. First, we analyze the evolution of the Higgs boson mass under the renormalization group by adopting the idea of \'Alvarez et al. For this analysis we derive two certain constraints by modifying Connes's way of constructing the standard model. Next, we find renormalization group invariant (RGI) constraints in the NCG method. We also consider the relation between the condition that a constraint among coupling constants of a model becomes RGI and the condition that the model becomes multiplicative renormalizable by using a simple example.; Comment: 22 pages, Latex file, 2 figures available upon request to umezawa@phys.cst.nihon-u.ac.jp, important changes are made, This is the last version which will appear in Prog. Theor. Phys. {\bf 100} (1998) as "Constraints among Coupling Constants in Noncommutative Geometry Models"

## Dependence of single-particle energies on coupling constants of the nuclear energy density functional

Kortelainen, M.; Dobaczewski, J.; Mizuyama, K.; Toivanen, J.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.24%
We show that single-particle energies in doubly magic nuclei depend almost linearly on the coupling constants of the nuclear energy density functional. Therefore, they can be very well characterized by the linear regression coefficients, which we calculate for the coupling constants of the standard Skyrme functional. We then use these regression coefficients to refit the coupling constants to experimental values of single-particle energies. We show that the obtained rms deviations from experimental data are still quite large, of the order of 1.1 MeV. This suggests that the current standard form of the Skyrme functional cannot ensure spectroscopic-quality description of single-particle energies, and that extensions of this form are very much required.; Comment: 8 RevTeX pages, 16 EPS figures, submitted to Physical Review C

## A $T_0$-discrete universe model with five low-energy fundamental interactions and the coupling constants hierarchy

Efremov, Vladimir N.; Mitskievich, Nikolai V.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.3%
A quantum model of universe is constructed in which values of dimensionless coupling constants of the fundamental interactions (including the cosmological constant) are determined via certain topological invariants of manifolds forming finite ensembles of 3D Seifert fibrations. The characteristic values of the coupling constants are explicitly calculated as the set of rational numbers (up to the factor $2\pi$) on the basis of a hypothesis that these values are proportional to the mean relative fluctuations of discrete volumes of manifolds in these ensembles. The discrete volumes are calculated using the standard Alexandroff procedure of constructing $T_0$-discrete spaces realized as nerves corresponding to characteristic canonical triangulations which are compatible with the Milnor representation of Seifert fibered homology spheres being the building material of all used 3D manifolds. Moreover, the determination of all involved homology spheres is based on the first nine prime numbers ($p_1=2, >..., p_9=23$). The obtained hierarchy of coupling constants at the present evolution stage of universe well reproduces the actual hierarchy of the experimentally observed dimensionless low-energy coupling constants.; Comment: RevTeX4 6 pages

## Coupling constants of bottom (charmed) mesons with pion from three point QCD sum rules

Janbazi, M.; Ghahramany, N.; Pourjafarabadi, E.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.27%
In this article, the three point QCD sum rules is used to compute the strong coupling constants of vertices containing the strange bottomed ( charmed ) mesons with pion. The coupling constants are calculated, when both the bottom ( charm ) and pion states are off-shell. A comparison of the obtained results of coupling constants with the existing predictions is also made. Key words: strong coupling constant, meson, QCD sum rules, bottom, charm.; Comment: 17pages, Latex. arXiv admin note: text overlap with arXiv:1104.2864, arXiv:1103.0943, arXiv:hep-ph/0304193 by other authors

## Superexchange via Cluster States: Calculations of Spin-Phonon Coupling Constants for CuGeO3

Feldkemper, S.; Weber, W.
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.28%
Calculations for spin-phonon coupling constants in CuGeO3 are presented, applying fourth order superexchange perturbation theory to an extended Hubbard model. In our treatment, the intermediate oxygen ligand states are described by band-like cluster states, due to the presence of significant O(p)-O(p) hopping. We also include the effect of the Ge ions on the O ligand states. We find a considerable q-dependence of the spin-phonon coupling. For the pi-modes involved in the spin-Peierls transition, our results of the coupling constants are in fair agreement with the work of Werner, Gros, and Braden. Yet some discrepancies remain, especially concerning the coupling to the vibrations, which modulate the O(2)-O(2)-Ge angle delta. Our studies of the pressure dependence of the magnetic coupling constants J_1 and J_2 suggest, that relatively large non-linear effects are present, even at small pressure values, probably due to the existence of a soft', van-der-Waals-type bond direction in CuGeO3.; Comment: submitted to Phys.Rev. B

## The Universe as a Set of Topological Fluids with Hierarchy and Fine Tuning of Coupling Constants in Terms of Graph Manifolds

Efremov, Vladimir N.; Magdaleno, Alfonso M. Hernandez; Lopez, Fernando I. Becerra
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.3%
The hierarchy and fine tuning of the gauge coupling constants are described on the base of topological invariants (Chern classes interpreted as filling factors) characterizing a collection of fractional topological fluids emerging from three dimensional graph manifolds, which play the role of internal spaces in the Kaluza-Klein approach to the topological BF theory. The hierarchy of BF gauge coupling constants is simulated by diagonal elements and eigenvalues of rational linking matrices of tree graph manifolds pasted together from Brieskorn (Seifert fibered) homology spheres. Specific examples of graph manifolds are presented which contain in their linking matrices the hierarchy of coupling constants distinctive for the dimensionless coupling constants in our Universe. The fine tuning effect is simulated owing to the special numerical properties of diagonal elements of the linking matrices. We pay a particular attention to fine tuning problem for the cosmological constant and propose its model solution.; Comment: 46 pages, LaTeX; added interpretation in terms of Julia-Toulouse approach in section 3; added 6 references

## Precise dipole moments and quadrupole coupling constants of the cis and trans conformers of 3-aminophenol: Determination of the absolute conformation

Filsinger, Frank; Wohlfart, Kirstin; Schnell, Melanie; Grabow, Jens-Uwe; Küpper, Jochen
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.32%
The rotational constants and the nitrogen nuclear quadrupole coupling constants of cis-3-aminophenol and trans-3-aminophenol are determined using Fourier-transform microwave spectroscopy. We examine several $J=2\leftarrow{}1$ and $1\leftarrow{}0$ hyperfine-resolved rotational transitions for both conformers. The transitions are fit to a rigid rotor Hamiltonian including nuclear quadrupole coupling to account for the nitrogen nucleus. For cis-3-aminophenol we obtain rotational constants of A=3734.930 MHz, B=1823.2095 MHz, and C=1226.493 MHz, for trans-3-aminophenol of A=3730.1676 MHz, B=1828.25774 MHz, and C=1228.1948 MHz. The dipole moments are precisely determined using Stark effect measurements for several hyperfine transitions to $\mu_a=1.7735$ D, $\mu_b=1.5195$ D for cis-3-aminophenol and $\mu_a=0.5563$ D, $\mu_b=0.5376$ D for trans-3-aminophenol. Whereas the rotational constants and quadrupole coupling constants do not allow to determinate the absolute configuration of the two conformers, this assignment is straight-forward based on the dipole moments. High-level \emph{ab initio} calculations (B3LYP/6-31G^* to MP2/aug-cc-pVTZ) are performed providing error estimates of rotational constants and dipole moments obtained for large molecules by these theoretical methods.; Comment: 9 pages...

## The Holographic Dictionary for Beta Functions of Multi-trace Coupling Constants

Aharony, Ofer; Gur-Ari, Guy; Klinghoffer, Nizan
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
46.38%
Field theories with weakly coupled holographic duals, such as large N gauge theories, have a natural separation of their operators into single-trace operators' (dual to single-particle states) and `multi-trace operators' (dual to multi-particle states). There are examples of large N gauge theories where the beta functions of single-trace coupling constants all vanish, but marginal multi-trace coupling constants have non-vanishing beta functions that spoil conformal invariance (even when all multi-trace coupling constants vanish). The holographic dual of such theories should be a classical solution in anti-de Sitter space, in which the boundary conditions that correspond to the multi-trace coupling constants depend on the cutoff scale, in a way that spoils conformal invariance. We argue that this is realized through specific bulk coupling constants that lead to a running of the multi-trace coupling constants. This fills a missing entry in the holographic dictionary.; Comment: 31 pages. v2: added references. v3: added references, JHEP version

## Modern NMR methodologies for the measurement of homo- and heteronuclear coupling constants in small molecules

Saurí i Jiménez, Josep
Fonte: [Barcelona] : Universitat Autònoma de Barcelona, Publicador: [Barcelona] : Universitat Autònoma de Barcelona,
Tipo: Tesis i dissertacions electròniques; info:eu-repo/semantics/doctoralThesis; info:eu-repo/semantics/publishedVersion Formato: application/pdf