Quantum Chemistry Models
Mostrando 1-11 de 11 artigos, teses e dissertações.
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1. AITP 2019 - ANO INTERNACIONAL DA TABELA PERIÓDICA DOS ELEMENTOS QUÍMICOS
United Nations elected 2019 a year devoted to the Periodic Table of the Elements, in deference to the original contribution by Dmitri Ivanovich Mendeleev in 1869. Since then, the impact of the Periodic Table in Science has been tremendous, becoming an icon today as the Chemistry Portal, leading to a better acquaintance of the chemical elements. In this artic
Quím. Nova. Publicado em: 27/05/2019
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2. Entre mecánica cuántica y estructuras químicas: ¿a qué refiere la química cuántica?
The aim of this article is to address the question of the ontology of quantum chemistry. To this end we will focus on the concept of chemical bond, from the perspective of the two approaches by means of which the Schrödinger equation is applied to molecular chemical systems: the Theory of Valence Bond (VB) and the Theory of Molecular Orbital (MO). On the ba
Sci. stud.. Publicado em: 2012
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3. Modelos da Química Quântica no espaço de momento: diferentes representações de um mesmo sistema
The conventional approach to simple quantum chemistry models is contrasted with that known as momentum representation, where the wavefunctions are momentum dependent. Since the physical interactions are the same, state energies should not change, and whence the energy differences correlating with the real world as spectral lines or bands. We emphasize that o
Química Nova. Publicado em: 2009
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4. Modelagem termodinamica de equilibrio liquido-liquido em sistemas envolvendo liquidos ionicos com modelos de composição local/contribuição de grupo e estruturas moleculares determinadas via quimica quantica / Thermodynamic modeling of liquid-liquid equilibrium in systems involving ionic liquids with models of local composition/group contribution and molecular structures determined by quantum chemistry
Líquidos iônicos são sais orgânicos de alto peso molecular que são líquidos a temperatura ambiente. Estas substâncias têm recebido considerável atenção como solventes ecologicamente corretos, já que não possuem pressão de vapor mensurável e, portanto, não apresentam emissões tóxicas ou poluentes como os solventes orgânicos tradicionais. Ne
Publicado em: 2009
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5. The use of computational chemistry in the studies of chemical processes involved in electrospray ionization / A utilização da química computacional em processos químicos relacionados à ionização por electrospray
In recent decades, the development of atmospheric ionization techniques improved mass spectrometry, principally for characterization and structural elucidation of high-molecular weight compounds. The development of spray ionization was responsible for the spread of applications and studies of mass spectrometry, where the electrospray ionization is the most v
Publicado em: 2009
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6. Espaço do momento: modelos da química quântica / Momentum Space: Quantum Chemistry Models
In a conventional course in Quantum Chemistry, the models usually presented to illustrate the use of some quantum mechanical tools that are relevant for a comprehension of the structure of matter at the atomic and molecular levels are approached in a way that has been termed, in a more formal presentation, as position representation. In this representation,
Publicado em: 2008
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7. Síntese de bisporfirinas contendo o espaçador 2,2-bipiridina: modelos na elaboração de sensores luminescentes de íons metálicos / Synthesis of bisporphyrins held together by the 2,2-bipyridine spacer: models in the elaboration of luminescent sensors for metal ions
In this work have been synthesized bisporphyrins held together by means of amide linkage at the 4,4position of 2,2-bipyridine, reacting the mono-functionalised aminophenyl-porphyrin (NH2PTriPP) and 4,4-diacid chloride bipyridine (DACBipy). A preliminary study was conducted for the establishment of the reaction conditions for the attainment of mono(nitropheny
Publicado em: 2008
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8. Modelo Sparkle: novos avanÃos para o estudo quÃmico-quÃntico de complexos de lantanÃdeos
Since 1994, the Sparkle Model for Lanthanide Complexes has been used for the calculation of ground state geometries of only Eu(III) complexes. In the present thesis, we evolved the Sparkle Model and advanced Sparkle/AM1 and Sparkle/PM3: new paradigms for semiempirical quantum chemical calculations on lanthanide complexes. Parameterizations for all fifteen tr
Publicado em: 2007
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9. Theoretical study on cationic dyes and models that explain the interaction with the montmorillonite clay / Estudo teórico sobre corantes catiônicos e possíveis modelos que expliquem a interação com a argila do tipo montmorilonita.
Neste trabalho, são utilizados diversos métodos de química teórica para estudar as propriedades eletrônicas e o espectro de absorção de seis corantes catiônicos: laranja de acridina (LA), proflavina (PF), safranina (SF), vermelho neutro (VN), azul de metileno (AM) e tionina (TN). Inicialmente é realizado um estudo para verificar a influência do sol
Publicado em: 2006
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10. Estudo eletroquímico das interações entre sulfetos de ferro / Electrochemical study of iron sulphides interactions
The electrochemical behavior of iron sulfides, pyrite, pyrrhotite and arsenopyrite was studied in acetic acid/sodium acetate buffer, pH = 4.5. The investigations included the dissolution of minerals (isolated and mixed in pairs) and the studies of the deposition of silver ions on the electrode surfaces, taking into account the semiconducting properties of ea
Publicado em: 1999
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11. The vibrational energy flow transition in organic molecules: Theory meets experiment
Most large dynamical systems are thought to have ergodic dynamics, whereas small systems may not have free interchange of energy between degrees of freedom. This assumption is made in many areas of chemistry and physics, ranging from nuclei to reacting molecules and on to quantum dots. We examine the transition to facile vibrational energy flow in a large se
The National Academy of Sciences.