Topic

# Charge (physics)

About: Charge (physics) is a research topic. Over the lifetime, 19584 publications have been published within this topic receiving 365056 citations. The topic is also known as: charge (theoretical physics) & physical charge (general).

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01 Jan 1990

TL;DR: In this article, the quantum atom and the topology of the charge desnity of a quantum atom are discussed, as well as the mechanics of an atom in a molecule.

Abstract: List of symbols 1. Atoms in chemistry 2. Atoms and the topology of the charge desnity 3. Molecular structure and its change 4. Mathematical models of structural change 5. The quantum atom 6. The mechanics of an atom in a molecule 7. Chemical models and the Laplacian of the charge density 8. The action principle for a quantunm subsystem Appendix - Tables of data Index

11,853 citations

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TL;DR: In this article, an algorithm for decomposition of electronic charge density into atomic contributions is presented. But instead of explicitly finding and representing the dividing surfaces, which is a challenging task, the algorithm assigns each point on a regular (x,y,z) grid to one of the regions by following a steepest ascent path on the grid.

7,231 citations

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TL;DR: In this article, the Hartree-Fock equations can be regarded as ordinary Schrodinger equations for the motion of electrons, each electron moving in a slightly different potential field, which is computed by electrostatics from all the charges of the system, positive and negative, corrected by the removal of an exchange charge, equal in magnitude to one electron, surrounding the electron whose motion is being investigated.

Abstract: It is shown that the Hartree-Fock equations can be regarded as ordinary Schr\"odinger equations for the motion of electrons, each electron moving in a slightly different potential field, which is computed by electrostatics from all the charges of the system, positive and negative, corrected by the removal of an exchange charge, equal in magnitude to one electron, surrounding the electron whose motion is being investigated By forming a weighted mean of the exchange charges, weighted and averaged over the various electronic wave functions at a given point of space, we set up an average potential field in which we can consider all of the electrons to move, thus leading to a great simplification of the Hartree-Fock method, and bringing it into agreement with the usual band picture of solids, in which all electron are assumed to move in the same field We can further replace the average exchange charge by the corresponding value which we should have in a free-electron gas whose local density is equal to the density of actual charge at the position in question; this results in a very simple expression for the average potential field, which still behaves qualitatively like that of the Hartree-Fock method This simplified field is being applied to problems in atomic structure, with satisfactory results, and is adapted as well to problems of molecules and solids

3,390 citations

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TL;DR: In this article, it was shown that the global charges of a gauge theory may yield a nontrivial central extension of the asymptotic symmetry algebra already at the classical level.

Abstract: It is shown that the global charges of a gauge theory may yield a nontrivial central extension of the asymptotic symmetry algebra already at the classical level. This is done by studying three dimensional gravity with a negative cosmological constant. The asymptotic symmetry group in that case is eitherR×SO(2) or the pseudo-conformal group in two dimensions, depending on the boundary conditions adopted at spatial infinity. In the latter situation, a nontrivial central charge appears in the algebra of the canonical generators, which turns out to be just the Virasoro central charge.

3,072 citations

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TL;DR: In this paper, an approach for predicting charge distributions in molecules for use in molecular dynamics simulations is presented, where an atomic chemical potential is constructed by using these quantities plus shielded electrostatic interactions between all charges.

Abstract: We report here an approach for predicting charge distributions in molecules for use in molecular dynamics simulations. The input data are experimental atomic ionization potentials, electron affinities, and atomic radii. An atomic chemical potential is constructed by using these quantities plus shielded electrostatic interactions between all charges. Requiring equal chemical potentials leads to equilibrium charges that depend upon geometry. This charge equilibration (QEq) approach leads to charges in excellent agreement with experimental dipole moments and with the atomic charges obtained from the electrostatic potentials of accurate ab initio calculations. QEq can be used to predict charges for any polymer, ceramic, semiconductor, or biological system, allowing extension of molecular dynamics studies to broad classes of new systems. The charges depend upon environment and change during molecular dynamics calculations. We indicate how this approach can also be used to predict infrared intensities, dielectric constants, and other charge-related properties.

2,820 citations