Results obtained with the correlation energy density functionals of becke and Lee, Yang and Parr

Miehlich, Burkhard; Savin, Andreas; Stoll, Hermann; Preuß, H.

doi:10.1016/0009-2614(89)87234-3

Cited by 6,861 publications

(3,156 citation statements)

References 20 publications

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“…In our systems, the impact parameter is defined with respect to the center of mass of each species. The largest of our molecules, C 8 Ϫ , has a distance from the center of mass to the end of the chain of ϳ4.55 Å. The impact parameter for this molecule is 5.6 Å for PPI and 5.7 Å for ODPI.…”

Section: Resultsmentioning

confidence: 96%

Collision rate constants for polarizable ions

Eichelberger

Snow

Bierbaum

2003

J. Am. Soc. Mass Spectrom.

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Langevin described a model for the interaction between an ion and a neutral nearly a century ago and since then, many modifications have been introduced to adjust for specific circumstances. This work discusses the induced dipole-induced dipole interaction between an ion and a neutral without a permanent dipole and introduces an anisotropic adjustment. A point polarizable ion model (PPI) and an orientation dependent polarizable ion model (ODPI) are discussed and applied to systems where the ion is highly polarizable and the neutral is only weakly polarizable. with work outlining the attractive potential between a point charge and a point-polarizable neutral. The result was an expression for the collisional rate constant, k L , in terms of a few simple variables; e, the elementary charge, ␣ n , the polarizability of the neutral, and , the reduced mass of the ionneutral pair.The approach is appealing in its simplicity, and has been used as a standard for ion-molecule and ion-atom collisions. This method has been used extensively to calculate collision rate constants in many environments, including the interstellar medium, where atomic hydrogen, molecular hydrogen, and atomic oxygen and nitrogen are the most abundant species.Another major area of work involves the interaction of an ion and a neutral species with a permanent dipole moment. Several approaches have been taken, ranging from an orientation-fixed dipole approximation to orientation-dependent approaches which rigorously conserve angular momentum and energy. These methods have been discussed in detail [2,3]. Additional work in this area involves parameterizing the theory to obtain a solution that is easily accessible to experimentalists [4,5].Deviations from a point charge model have been described by Su et al. [9,10] and an induced dipoleinduced dipole adjustment has been discussed by Su and Bowers [11]. The possibility for large deviation is mentioned with respect to anionic systems, but due to the difficulty of acquiring ionic polarizabilities, only the Cl Ϫ and H Ϫ anions are discussed. These systems afford less than 5% deviation from the classical Langevin rate constants. In this paper we highlight the importance of the anisotropy of the induced dipole-induced dipole interaction and introduce an orientation dependent polarizable ion model. We demonstrate that these interactions, especially when anisotropy is included, have significant impact on the collision rate constants of large molecular cations and anions. TheoryThe Langevin rate constant is derived from a potential that assumes the ion is a point charge. Two factors, the long-range nature of the potential involving ions and the way in which the random orientation of an ion causes the location of the charge to average to the center, make this approximation accurate in most cases. Deviation can occur, however, in the second of these two factors. If the charge is mobile within the ion, the average location of the charge can shift from the center, effectively increasing the critical impact parameter...

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Section: Resultsmentioning

confidence: 96%

Collision rate constants for polarizable ions

Eichelberger

Snow

Bierbaum

2003

J. Am. Soc. Mass Spectrom.

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“…Afterwards, the remaining chalcones were investigated and the energetically most stable conformation that was similar to the conformation selected before was chosen for the calculation of the molecular properties. Before calculating the properties, the molecular geometries were optimized again, but now using the density functional theory (DFT) 18,19 with the hybrid exchange-correlation functional B3LYP [20][21][22] and the basis set 6-31G(d) as implemented in the software package G09 23 , which was also used to calculate the molecular properties (descriptors or variables). In this work, the following molecular descriptors were calculated: HOMO-1 (second highest occupied molecular orbital energy), HOMO (highest occupied molecular orbital energy), LUMO (lowest unoccupied molecular orbital energy), LUMO+1 (second lowest unoccupied molecular orbital energy), partition coefficient (logP) (this property was obtained from the hydrophobic parameters of the substituents using HyperChem TM 7.5), Mulliken Vol.…”

Section: Principal Component Analysis (Pca) Of Chalconesmentioning

confidence: 99%

Biological and structure-activity evaluation of chalcone derivatives against bacteria and fungi

Silva¹,

Andrade²,

Napolitano³

et al. 2013

J. Braz. Chem. Soc.

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O presente trabalho descreve as atividades antibacterianas e antifúngicas de diversas chalconas obtidas diretamente através da condensação aldólica tipo Claisen-Schmidt das quais se determinou a concentração inibitória mínima frente a diferentes microrganismos (bactérias Gram-positivas e Gram-negativas e fungos). Estruturas no estado sólido cristalino de sete chalconas foram determinadas por análise de difração de raios X (XRD). Estudos quimiométricos foram realizados com intuito de identificar uma potencial relação entre estrutura e atividade.The present work describes the antibacterial and antifungal activities of several chalcones obtained by a straight Claisen-Schmidt aldol condensation determined by the minimal inhibitory concentration against different microorganisms (Gram-positive and Gram-negative bacteria and fungi). Solid state crystal structures of seven chalcones were determined by X-ray diffraction (XRD) analysis. Chemometric studies were carried out in order to identify a potential structureactivity relationship.

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“…Bonding order and packing ratio in the single crystal of Dimer and Chain were calculated using B3LYP functional [7][8][9][10] adding the D3 version of Grimme's dispersion with Becke-Johnson damping [11] and SDD ECP for Mn and 6-311G(d) basis sets for other elements using Gaussian 09 software. [12] Density functional theory has been proved suitable for such kind of calculations.…”

Section: Methodsmentioning

confidence: 99%

Bond Order Analysis, Packing Ratio, and Electronic Structures of Two Structural Polymorphs Based on Manganese Complexes

Chen

Zhang

et al. 2017

Chin. J. Chem.

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The bond order and packing ratios in the single-crystal of the two structural polymorphs as well as the detailed electronic structures of the molecular model were studied using density functional theory. The strength of different Mn coordination bonds was analyzed in detail through Mayer bond order. Besides bond length, many other factors such as the orientation of ligand and nature of metal also significantly influence the bond order. Packing ratios calculated using cluster model reveals that packing along b direction in Dimer is more favorable than other directions due to the associated interactions of π-π and Cl…H when packing in this direction. Electronic structure helps explain the formation of Dimer from monomer or direct forming of Chain from ligand/Cl and metal. This would shed light on further understanding the importance of supramolecular interaction on crystal engineering.

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Results obtained with the correlation energy density functionals of becke and Lee, Yang and Parr

Cited by 6,861 publications

References 20 publications

Collision rate constants for polarizable ions

Collision rate constants for polarizable ions

Biological and structure-activity evaluation of chalcone derivatives against bacteria and fungi

Bond Order Analysis, Packing Ratio, and Electronic Structures of Two Structural Polymorphs Based on Manganese Complexes

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