Validação computacional de métodos compostos no estudo de propriedades moleculares

Heerdt, Gabriel; Morgon, Nelson H.

doi:10.1590/s0100-40422011000500024

Cited by 10 publications

(16 citation statements)

References 32 publications

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“…43 Frequencies calculations were also performed at the same level of theory in order to verify the nature of minima. [44][45][46] Solvent effects were introduced in all the calculations through the SMD 47 continuum solvation method. Binding energies were estimated among the ethylendiamine di(2-hydroxy-4-methylphenylacetic) acid (EDDHMA), selenite (SeO 3 2-) and selenate (SeO 4 2-) anions and each of the metallic elements.…”

Section: Theoretical Calculationsmentioning

confidence: 99%

Effect of Selenite and Selenate Application on Mineral Composition of Lettuce Plants Cultivated Under Hydroponic Conditions: Nutritional Balance Overview Using a Multifaceted Study

Silva¹,

Cidade²,

Heerdt³

et al. 2017

J. Braz. Chem. Soc.

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The effect of selenate and selenite enrichment on mineral composition of a red type of lettuce cv. "Veneza roxa" was evaluated using inductively coupled plasma-optical emission spectroscopy (ICP OES), molecular modeling and principal component analysis (PCA). Both Se species did not show toxicity, while selenate promoted the greatest Se accumulation by the plant. There was an increase of 886 µg of Se per 100 g of fresh sample at different concentrations of selenate, but for selenite the maximum variation was only of 114 µg per 100 g. Selenate promoted the absorption of Mo and S and the reduction of K, Mn and P, meanwhile selenite increased Mn and decreased Mo accumulation. Copper and Fe absorption was negatively affected, Ca and Mg showed a slight increase, and Na and Zn were not affected by Se species. Despite the changes in the nutritional balance, Se-enriched lettuce can still be considered a potential dietary source of this essential element.

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Section: Theoretical Calculationsmentioning

confidence: 99%

Effect of Selenite and Selenate Application on Mineral Composition of Lettuce Plants Cultivated Under Hydroponic Conditions: Nutritional Balance Overview Using a Multifaceted Study

Silva¹,

Cidade²,

Heerdt³

et al. 2017

J. Braz. Chem. Soc.

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“…98 Neste contexto torna-se necessária a execução de cálculos de correlação eletrônica em níveis altamente sofisticados, como os baseados na Teoria , em que os quatro primeiros termos (E (10) C , E (10) Ex , E (10) Ind,Resp e E (20) Ex-Ind,Resp referentes à Equação 10) comportam a energia do campo autoconsistente (SCF, Self-Consistent Field), 113 enquanto os dois restantes (E (20) D e E (20) Ex-D ) a dispersão eletrônica. 114 Determinando a contribuição de cada um destes termos com cálculos realizados em nível ab initio 115 ou DFT, [116][117][118] o método SAPT revela sob quais condições eletrônicas o sistema intermolecular é estabilizado em um mínimo de energia, e com isto torna-se possível designá-lo como forte ou fracamente ligado no que se refere à existência de ligações de hidrogênio ou interações de van der Waals, 119 respectivamente.…”

Section: Métodos Teóricos De Decomposição De Energiaunclassified

SAPT: ligação de hidrogênio ou interação de van der Waals?

Oliveira¹,

Araújo²

2012

Quím. Nova

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Recebido em 24/11/11; aceito em 27/6/12; publicado na web em 17/9/12 SAPT: HYDROGEN BOND OR van der WAALS INTERACTION? It is through the application of an electronic partition approach called Symmetry-Adapted Perturbation Theory (SAPT) that the nature of hydrogen bonds and van der Waals interactions can be unveiled according to the contribution of electrostatic, charge transfer, exchange repulsion, polarization, and dispersion terms. Among these, electrostatic partition governs the formation of the hydrogen bonds, whose energies are arguably high. However, the weakness of the interaction strength is caused by dispersion forces, whose contribution decisively lead to the stabilization of complexes formed via van der Waals interactions. Keywords: hydrogen bonds; van der Waals interactions; SAPT. INTRODUÇÃOFisicamente, as interações fortes, fracas, eletromagnéticas e gravitacionais governam o contato entre as partículas.1 Destas, é bem estabelecido pela cromodinâmica quântica que as interações fortes ocorrem entre prótons e nêutrons através da ação dos quarks e glúons, 2 cujo resultado é a formação do núcleo atômico denso e compacto. Presente em nível nuclear, as interações fracas são 10 13 menos intensas e são caracterizadas pelas manifestações dos bósons W (Weak nuclear force) e Z (Zero).3 Interações eletromagnéticas são típicas de partículas elementares carregadas 4 e são 10 2 mais fracas em relação às interações fortes. Por fim, a geometrodinâmica estabelece que as interações gravitacionais são 10 42 mais amenas e estão presentes em sistemas com massas macroscopicamente mensuráveis, 5 como estrelas, galáxias e todo o universo. No cerne da química atômico--molecular, as interações consideradas fracas com características puramente eletrostáticas são as mais importantes, pois os sistemas são interpretados como sendo ligados 6,7 e não covalentes, 8,9 e nestas circunstâncias átomos formam as ligações químicas 10 e moléculas atingem condições eletrônicas propícias para formarem estruturas intermoleculares estáveis. As interações intituladas de van der Waals foram assim concebidas em reconhecimento ao físico neerlândes Johannes Diederik van der Waals pelos seus estudos com substâncias gasosas e líquidas, em uma proposta que objetivava a otimização dos modelos de Boyle e Charles 54 através da descrição do tamanho molecular e a força intermolecular atuante, a qual é composta pelas contribuições de Keesom (interação entre dipolo permanente--dipolo permanente), 55 Debye (interação entre dipolo permanente--dipolo induzido) 56 e London (interação entre dipolo induzido-dipolo induzido). 57 As interações de van der Waals têm sido foco de muitos pesquisas, principalmente no aprimoramento de alguns métodos que falham na captura dos efeitos provenientes das forças de dispersão. 58As ligações de hidrogênio ou interações de van der Waals são, de fato, alicerces de suma importância para a Biologia, Medicina, Química, Engenharia, Física 59 e áreas correlatas. Entretanto, dentro da comunidade científica ainda persiste um intenso deba...

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“…10 In comparison with different basis set, the best results were obtained with the double and triple zeta-valence basis set, 6-31G(d) and 6-311++G(2df,p), respectively. Among 25 exchangecorrelation functionals and the HF and MP2 methods, we observed optimal results to eight functionals, B1LYP, B3LYP, HCTH, HCTH147, mPW1LYP, O3LYP, VSXZ, X3LYP.…”

Section: Computational Detailsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9] However, practical calculations containing many particles become a task that requires a very high computational cost. 10 Some strategies have been successful, making it possible to study large systems, highlighting the composite methods [11][12][13][14][15][16][17][18][19] and the ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) method. 20 Developed in the 1980s, the composite methods aim to extrapolate the electronic energies from a sequence of calculations, computationally inexpensive, to an electronic energy with a high level of correlation and large basis set.…”

Section: Introductionmentioning

confidence: 99%

Theoretical study of thermochemical properties using composite methods adapted to ONIOM

Heerdt

Morgon

2012

J. Braz. Chem. Soc.

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Métodos compostos adaptados ao método ONIOM foram utilizados no cálculo teórico de afinidades por próton (PA) e eletrônica (EA) para um grupo de 50 moléculas (álcoois, cetonas, radicais e alcenos). A energia eletrônica foi descrita considerando-se o escalonamento de ZPE (λ) e a correção de alto nível (HLC). O valor ótimo para λ foi obtido através dos dados de PA. Os cálculos de EA foram utilizados na otimização dos termos presentes em HLC. Foram explorados diferentes tipos de funcionais de troca-correlação. A metodologia ONIOM2(QCISD(T)/6-311++G(2dF,p):HF/6-31G(d))//ONIOM2(B3LYP/6-31G(d):HF/6-31G(d)) forneceu os menores desvios absolutos médios para PA e EA, 5,38 kJ mol -1 e 0,11 eV, respectivamente, em comparação com dados experimentais.Composite methods adapted to the ONIOM approach were used in the description of proton (PA) and electron (EA) affinities for a group of 50 molecules (alcohols, ketones, radicals and alkenes). The electronic energy was described considering the scaling ZPE (λ) and higher level (HLC) corrections. The optimal value for λ was obtained from the PA data. The EA calculations were used for optimization of the terms in HLC. Different performances of exchange-correlation functionals were considered. The methodology ONIOM2(QCISD(T)/6-311++G(2dF,p):HF/6-31G(d))//ONIOM2(B3LYP/6-31G(d):HF/6-31G(d)) provided the smallest median absolute deviation (MAD) for PA and EA, 5.38 kJ mol -1 and 0.11 eV, respectively, in comparison to the experimental data.Keywords: proton and electron affinities, composite methods, ONIOM Introduction Molecular modeling calculations using high level (ab initio and DFT methods) and large basis sets have provided determinations of the precise electronic properties of atomic and molecular systems. 1-9 However, practical calculations containing many particles become a task that requires a very high computational cost. 10 Some strategies have been successful, making it possible to study large systems, highlighting the composite methods [11][12][13][14][15][16][17][18][19] and the ONIOM (our own n-layered integrated molecular orbital and molecular mechanics) method. 20 Developed in the 1980s, the composite methods aim to extrapolate the electronic energies from a sequence of calculations, computationally inexpensive, to an electronic energy with a high level of correlation and large basis set. 2 In addition to the energy terms from the energy calculations, some empirical parameters can be added to correct deficiencies of the method, like additional correlation effects, relativistic effect, etc.The Gaussian-n theory, developed by Pople and co-workers, 13-17 exploits this idea to predict thermochemical data of molecules containing elements of the first three periods of the periodic table. The purpose of this theory is to obtain a general procedure that can reproduce experimental data for properties such as proton and electron affinities, ionization energy, enthalpy of formation, etc., being applicable to any molecular system unambiguously. Recently, new approaches of these theo...

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Validação computacional de métodos compostos no estudo de propriedades moleculares

Cited by 10 publications

References 32 publications

Effect of Selenite and Selenate Application on Mineral Composition of Lettuce Plants Cultivated Under Hydroponic Conditions: Nutritional Balance Overview Using a Multifaceted Study

Effect of Selenite and Selenate Application on Mineral Composition of Lettuce Plants Cultivated Under Hydroponic Conditions: Nutritional Balance Overview Using a Multifaceted Study

SAPT: ligação de hidrogênio ou interação de van der Waals?

Theoretical study of thermochemical properties using composite methods adapted to ONIOM

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