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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 ...
For a specified geographic location, time, and date, IRI provides average monthly values for electron density, electron temperature and ion temperature, and the molecular composition of the ions in the range of altitudes from 50 km to 2000 km. [1] The latest standard is IRI-2012. [1] [2] A new version, IRI-2016, has since been released. [3]
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.
Total electron content (TEC) is an important descriptive quantity for the ionosphere of the Earth. TEC is the total number of electrons integrated between two points, along a tube of one meter squared cross section , i.e., the electron columnar number density .
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 many cases, crystallographic disorder smears the electron density map. Weakly scattering atoms such as hydrogen are routinely invisible. It is also possible for a single atom to appear multiple times in an electron density map, e.g., if a protein sidechain has multiple (<4) allowed conformations.
The arrangement of the electrons in the sample is described quantum mechanically by an "electron density". The electron density is a function of both position and energy, and is formally described as the local density of electron states, abbreviated as local density of states (LDOS), which is a function of energy.