Difference between revisions of "Electron-density distribution"

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The '''electron-density distribution''' is the three-dimensional [[realspace]] arrangement of the electrons in the material. Because electrons are [[quantum mechanics|quantum mechanically]] [[wave packet|delocalized]], each electron occupies a 'fuzzy' region of space. The total electron density--the summation of the electron distribution for every electron in every atom--is thus inherently spread spatially; e.g a map of electron distribution will have diffuse boundaries. Nevertheless, when the electron distribution is visualized, it is often shown as a surface, representing an isosurface of constant electron-density.
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The '''electron-density distribution''' is the three-dimensional [[realspace]] arrangement of the electrons in the material. Because electrons are [[quantum mechanics|quantum mechanically]] [[wave packet|delocalized]], each electron occupies a 'fuzzy' region of space ('''electron cloud'''). The total electron density--the summation of the electron distribution for every electron in every atom--is thus inherently spread spatially; e.g a map of electron distribution will have diffuse boundaries. Nevertheless, when the electron distribution is visualized, it is often shown as a surface, representing an isosurface of constant electron-density.
  
 
The exact electron-density distribution within a [[unit cell]] of a crystal can be reconstructed by carefully fitting the peak heights measured in an [[x-ray]] [[diffraction]] experiment ([[crystallography|crystallographic]] 'structure solution').
 
The exact electron-density distribution within a [[unit cell]] of a crystal can be reconstructed by carefully fitting the peak heights measured in an [[x-ray]] [[diffraction]] experiment ([[crystallography|crystallographic]] 'structure solution').

Revision as of 13:57, 20 January 2015

The electron-density distribution is the three-dimensional realspace arrangement of the electrons in the material. Because electrons are quantum mechanically delocalized, each electron occupies a 'fuzzy' region of space (electron cloud). The total electron density--the summation of the electron distribution for every electron in every atom--is thus inherently spread spatially; e.g a map of electron distribution will have diffuse boundaries. Nevertheless, when the electron distribution is visualized, it is often shown as a surface, representing an isosurface of constant electron-density.

The exact electron-density distribution within a unit cell of a crystal can be reconstructed by carefully fitting the peak heights measured in an x-ray diffraction experiment (crystallographic 'structure solution').

The electron distribution at a larger scale can be similarly reconstructed by fitting small-angle scattering data (SAXS or GISAXS). In this case, one is probing the average electron-density distribution at the nanoscale, without resolving the exact arrangement of electron-distribution (atoms) within this nanostructure. The specific electron-distribution within a measurement volume (as opposed to the average structure defined by a unit-cell) can be reconstructed using coherent methods such as CDI or ptychography.

References