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DOS

DOS: Density Of States
Definition:A DOS plot depicts the number of available electronic states for each energy level of a crystalline system. Important information, such as the number of occupied states at the Fermi level as well as the width of the band gap for insulators or semiconductors, can be read easily and directly from the DOS plot.
Explanation:A central concept in computational materials science is the electronic band structure, which represents the quantum-chemically computed energy eigen values of a crystal. It is the solid state analogue of a molecular-orbital diagram. The latter illustrates the discrete states of the molecular orbitals and their energies. Each atomic orbital of the participating atoms results in a molecular orbital. For crystals, the scenario is similar: each atomic orbital contributes to the entire(delocalized) crystal orbitals. Due to a large number of atoms and orbitals, the discrete states combine into bands. The figure below (left) shows the resulting band structure for face-centred cubic (→fcc) Fe as an example; it is built from an infinite number of atoms, and the different bands represents the different orbitals. For clarity, only the band structure is plotted and between chosen k points; however, a complete figure requires the structure at any k. For most applications, it is sufficient to know the number of states as a function of energy. Such a plot is known as DOS, where easier analysis is possible. In order to retain the picture from the band structure, chemists switch the x and y axes of the DOS and plot the energy as a function of the number of states.
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Diagram:

Band structure (left) and DOS (right) plots for austenitic iron (fcc Fe).
SFB-Link:The analyses of DOS plots are applied by subproject A1 to different structures of SFB materials in order to understand their chemistry and stability.
References:R. Dronskowski, Computational Chemistry of Solid State Materials, Wiley-VCH, Weinheim, 2005.