Toward a theory of chemical reactivity based on the charge density

Bader, R. F. W.; MacDougall, Preston J.

doi:10.1021/ja00310a007

Cited by 221 publications

(127 citation statements)

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“…This is called an atomic graph. [26] Another important parameter to characterize the atomic interaction is the total energy density H(r), which is defined as H(r)= G(r)+ V(r) where G(r) is a local kinetic energy density and V(r) is the average field experienced by one electron in a many-particle system (or the local potential energy density). The sign of H(r) determines whether the accumulation of charge at a point r is stabilization [H(r)<0] or destabilization [H(r) >0].…”

Section: The Topological Analysis Of the Electronic Densitymentioning

confidence: 99%

From Metal Cluster to Metal Nanowire: A Topological Analysis of Electron Density and Band Structure Calculation

Chen

Mou

et al. 2002

IJMS

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Abstract:We investigate a theoretical model of molecular metalwire constructed from linear polynuclear metal complexes. In particular we study the linear Cr n metal complex and Cr molecular metalwire. The electron density distributions of the model nanowire and the linear Cr n metal complexes, with n = 3, 5, and 7, are calculated by employing CRYSTAL98 package with topological analysis. The preliminary results indicate that the bonding types between any two neighboring Cr are all the same, namely the polarized open-shell interaction. The pattern of electron density distribution in metal complexes resembles that of the model Cr nanowire as the number of metal ions increases. The conductivity of the model Cr nanowire is also tested by performing the band structure calculation.

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Section: The Topological Analysis Of the Electronic Densitymentioning

confidence: 99%

From Metal Cluster to Metal Nanowire: A Topological Analysis of Electron Density and Band Structure Calculation

Chen

Mou

et al. 2002

IJMS

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“…It is well documented (6,13,14) that centres of charge concentration in the VSCC serve as sites of electrophilic attack, while the centres of charge depletion play the corresponding role in nucleophilic attack. The localized charge concentrations in the VSCC of carbon in a saturated hydrocarbon are, of course, all bonded concentrations and as such are relatively u~eactive towards electrophiles.…”

Section: A -mentioning

confidence: 99%

“…Substitution of a hydrogen in methane by fluorine greatly increases the extent of charge depletion in the VSCC of carbon in the face opposite the fluorine atom, thereby increasing the susceptibility of the carbon to nucleophilic attack (14).…”

Section: A -mentioning

confidence: 99%

Properties of atoms and bonds in carbocations

Bader¹

1986

Can. J. Chem.

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The quantum theory of atoms in molecules defines structures for and determines the properties of the atoms and bonds in the series of carbocations [(CH3),CH3_,]+ with n = 0-3, and their parent hydrocarbons. In this theory, an atom in a molecule and its properties are defined by quantum mechanics. The quantum condition defining the atom is given in terms of a property derived from the charge density, as are the other concepts of the molecular structure hypothesis. In terms of the amount of electronic charge density accumulated between the carbon nuclei and its spatial distribution, a C-C bond of the carbocations exhibits an order greater than one. There is a transfer of charge from the hydrogens of methyl to the central carbon that destroys the axial symmetry of these C-C bonds and concentrates the charge in a plane perpendicular to the plane of substitution, in a manner consistent with the hyperconjugative mechanism of electron transfer. The positive charge of a carbocation is thus delocalized over all the atoms in the molecule, and the extent of this delocalization increases with increased methyl substitution. The electron population of each atom in a carbocation increases with this increase in the delocalization of positive charge and its energy is correspondingly decreased (the atom becomes more stable). These effects are most pronounced for the carbon atom bearing the methyl groups and they account for the observed increase in the relative stabilities of the carbocations with increasing methyl substitution. The electron populations and energies of the atoms in saturated hydrocarbons are also determined. The group additivity scheme for the energy in the homologous series of normal alkanes is predicted and explained in terms of the properties of the quantum atoms. It is the possibility of such transferability of the quantum atoms and their properties between systems that identifies them with the atoms of chemistry.R. F. W. BADER. Can. J. Chem. 64, 1036 (1986).La thCorie quantique des atomes dans les molCcules dCfinit les structures et dCtermine les properiCtCs des atomes et des liaisons dans une sCrie de carbocations [(CH~),CH~-~]+, dans lesquels n = 0-3, ainsi que dans leurs hydrocarbures de base. Dans cette thCorie, la condition quantique qui dCfinit l'atome ainsi que les autres concepts de l'hypothbse relative i la structure molCculaire sont dCfinies en fonction d'une propriCtC dCrivCe de la densit6 de charge. En termes de la densit6 de la charge Clectronique qui est accumulCe entre les noyaux de carbone et de leur distribution spatiale, une liaison C-C des carbocations prksente un ordre qui est plus grand que un. I1 se produit un transfert de charge des hydrogbnes du mCthyle vers le carbone central et ceci dCtruit la symktrie axiale de ces liaisons C-C et concentre la charge dans un plan perpendiculaire au plan de la substitution, d'une manikre qui est en accord avec le mecanisme d'hyperconjugaison de transfert Clectronique. La charge positive d'un carbocation est donc dClocalisCe sur tous les atomes de la...

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“…Partial charges (q) derived from optimizing the fit ( ) between the classical model for the electrostatic potential (v̂ and the quantum mechanical molecular electrostatic potential (V) evaluated at points (i) around the molecule (so called ESP-charges) are frequently employed in MD simulations. (1) where (2) Alternative approaches to deriving atomic partial charges include empirical fitting to experimental properties (heats of vaporization or sublimation, liquid densities, or gas-phase dipole moments) [6,7] and partitioning of quantum mechanical wavefunctions (Mulliken, Bader and distributed multipole analyses) [8,9].…”

Section: Introductionmentioning

confidence: 99%

Restrained electrostatic potential atomic partial charges for condensed-phase simulations of carbohydrates

Woods

Chappelle

2000

Journal of Molecular Structure: THEOCHEM

161

132

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Charges derived from fitting a classical Coulomb model to quantum mechanical molecular electrostatic potentials (so called ESP-charges) are frequently used in simulations of macromolecules. Simulational methods that use ESP-charges generally reproduce the geometries of hydrogen bonded complexes, despite the fact that these charges are known to overestimate the strengths of these interactions. Through the use of a restraint function during the fitting of the partial charges to the electrostatic potentials the magnitudes of the charges may be attenuated (so called RESP-charges). For the AMBER force field RESP-charges have been proposed for proteins and nucleic acids. Here we examine a novel approach for determining the RESP-charges for carbohydrates based on molecular dynamics (MD) simulations of crystal structures. During a simulation, the crystallographic unit cell geometry is sensitive to both inter-molecular non-bonded forces and internal torsional rotations. However, for polar molecules, and specifically carbohydrates, the crystal geometries are particularly sensitive to the set of partial atomic charges employed in the simulation. Thus, given a force field in which the van der Waals and torsion terms are well parameterized, it is possible to assess the suitability of a set of partial charges by monitoring the properties of the crystal during an MD simulation. We have examined several charge sets for use with the GLYCAM parameters for carbohydrate and glycoprotein simulations and found that a restraint weight of 0.01 gives the best agreement with the neutron diffraction structure of α-D-glucopyranose. Unrestrained ESP-charges performed poorly as did the charges obtained from Mulliken and distributed multipole analyses of the quantum mechanical HF/6-31G* wavefunctions.

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Toward a theory of chemical reactivity based on the charge density

Cited by 221 publications

References 0 publications

From Metal Cluster to Metal Nanowire: A Topological Analysis of Electron Density and Band Structure Calculation

From Metal Cluster to Metal Nanowire: A Topological Analysis of Electron Density and Band Structure Calculation

Properties of atoms and bonds in carbocations

Restrained electrostatic potential atomic partial charges for condensed-phase simulations of carbohydrates

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