Nonconvexity of the atomic charge density and shell structure

A direct relation between the charge density of a free atom, ρa(r), and the cohesive energy of the corresponding metal is proposed. This relation is based on an approximation for the metallic charge density, ρm(r), that is constructed from ρa(r) through [Formula: see text] being the atomic volume of the metallic atom, and R0 the corresponding Wigner–Seitz radius. The cohesive energy Ecoh is then related to [Formula: see text] through [Formula: see text] A systematic study of 29 metallic elements including the 3d and 4d transition elements shows that the proposed relation is, in general, at least as accurate as recent ab initio results. In the same fashion, an expression for the metallic bulk modulus is derived. This expression requires, in addition to [Formula: see text], the values of ρa(R0) and its first derivative ρ′a(R0). The computed bulk moduli are, again, at least as good as the ab initio ones for the set of metallic elements studied. Key words: cohesive energies, bulk moduli, charge density, transition elements.

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A Bond Bundle Case Study of Diels-Alder Catalysis Using Oriented Electric Fields

10.26434/chemrxiv-2021-17wpx-v2 ◽

2022 ◽

Author(s):

Timothy Wilson ◽

Mark Eberhart

Keyword(s):

Electric Field ◽

Charge Density ◽

Electric Fields ◽

Chemical Reactions ◽

Catalytic Effect ◽

Reaction Pathway ◽

Three Dimensional ◽

Atomic Charge ◽

Diels Alder

Bond bundles are chemical bonding regions, analogous to Bader atoms, uniquely defined according to the topology of the gradient bundle condensed charge density, itself obtained by a process of infinitesimal partitioning of the three-dimensional charge density into differential zero-flux surface bounded regions. Here we use bond bundle analysis to investigate the response of the charge density to an oriented electric field in general, and the catalytic effect of such a field on Diels-Alder reactions in particular, which in this case is found to catalyze by allowing the transition state valance bond bundle configuration to be achieved earlier along the reaction pathway. Using precise numerical values, we arrive at the conclusion that chemical reactions and electric field catalysis can be understood in terms of intra-atomic charge density redistribution, i.e., that charge shifts within more so than between atoms account for the making and breaking of bonds.

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A Bond Bundle Case Study of Diels-Alder Catalysis Using Oriented Electric Fields

10.26434/chemrxiv-2021-17wpx ◽

2021 ◽

Author(s):

Timothy Wilson ◽

Mark Eberhart

Keyword(s):

Electric Field ◽

Charge Density ◽

Electric Fields ◽

Chemical Reactions ◽

Catalytic Effect ◽

Reaction Pathway ◽

Three Dimensional ◽

Atomic Charge ◽

Diels Alder

Bond bundles are chemical bonding regions, analogous to Bader atoms, uniquely defined according to the topology of the gradient bundle condensed charge density, itself obtained by a process of infinitesimal partitioning of the three-dimensional charge density into differential zero-flux surface bounded regions. Here we use bond bundle analysis to investigate the response of the charge density to an oriented electric field in general, and the catalytic effect of such a field on Diels-Alder reactions in particular, which in this case is found to catalyze by allowing the transition state valance bond bundle configuration to be achieved earlier along the reaction pathway. Using precise numerical values, we arrive at the conclusion that chemical reactions and electric field catalysis can be understood in terms of intra-atomic charge density redistribution, i.e., that charge shifts within more so than between atoms account for the making and breaking of bonds.

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Electron Charge Density Distribution from X-Ray Diffraction Study of the 4-Methoxybenzenecarbothioamide Compound

Journal of Crystallography ◽

10.1155/2013/326457 ◽

2013 ◽

Vol 2013 ◽

pp. 1-7 ◽

Cited By ~ 3

Author(s):

Mokhtaria Drissi ◽

Abdelkader Chouaih ◽

Youcef Megrouss ◽

Fodil Hamzaoui

Keyword(s):

Charge Transfer ◽

Hydrogen Bonds ◽

Density Distribution ◽

Charge Density ◽

Title Compound ◽

Atomic Charge ◽

Crystallographic Axis ◽

Electron Charge ◽

Charge Density Distribution ◽

Electron Charge Density

The molecular electron charge density distribution of the title compound is described accurately using the multipolar model of Hansen and Coppens. The net atomic charge and the in-crystal molecular dipole moment have been determined in order to understand the nature of inter- and intramolecular charge transfer. The study reveals the nature of intermolecular interactions including charge transfer and hydrogen bonds in the title compound. In this crystal, the molecules form dimers via N–HS intermolecular hydrogen bonds. The dimers are further linked by C–HO hydrogen bonds into chains along the c crystallographic axis. This study has also allowed us to determine the electrostatic potential and therefore locate the electropositive part and the electronegative part in molecular scale of the title compound.

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