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Electron density or electronic density is the measure of the probability of an electron being present at an infinitesimal element of space surrounding any given point. It is a scalar quantity depending upon three spatial variables and is typically denoted as either ρ ( r ) {\displaystyle \rho ({\textbf {r}})} or n ( r ) {\displaystyle n ...
In X-ray crystallography, a difference density map or Fo–Fc map shows the spatial distribution of the difference between the measured electron density of the crystal and the electron density explained by the current model. [1] A way to compute this map has been formulated for cryo-EM. [2]
Coot displays electron density maps and atomic models and allows model manipulations such as idealization, real space refinement, manual rotation/translation, rigid-body fitting, ligand search, solvation, mutations, rotamers, and Ramachandran idealization. The software is designed to be easy-to-learn for novice users, achieved by ensuring that ...
Series of density maps for GroEL: from left to right, 4 Å, 8 Å, 16 Å, and 32 Å resolution.The details are smeared away as the resolution becomes lower. Resolution in the context of structural biology is the ability to distinguish the presence or absence of atoms or groups of atoms in a biomolecular structure.
In order to obtain an interpretable electron density map, both amplitude and phase must be known (an electron density map allows a crystallographer to build a starting model of the molecule). The phase cannot be directly recorded during a diffraction experiment: this is known as the phase problem .
This gives the potential at locations on a particular surface, most commonly a surface of electron density corresponding to overall molecular size. [71] Local ionization potential map – Is defined as the sum over orbital electron densities, ρi(r) times absolute orbital energies, ∈i, and divided by the total electron density, ρ(r). The ...
ShelXle can display electron density maps like the macromolecular program Coot but is more intended for smaller molecules. A number of excellent graphical user interfaces (GUIs) exist for small molecule crystal structure refinement with SHELX (e.g., WINGX, [4] Olex2, [5] XSEED, [6] PLATON and SYSTEM-S, [7] and the Bruker programs XP and XSHELL)
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