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Spin density is electron density applied to free radicals. It is defined as the total electron density of electrons of one spin minus the total electron density of the electrons of the other spin. One of the ways to measure it experimentally is by electron spin resonance, [14] neutron diffraction allows direct mapping of the spin density in 3D ...
where is the current density, is the external electric field, is the electronic density (number of electrons/volume), is the mean free time and is the electron electric charge. Other quantities that remain the same under the free electron model as under Drude's are the AC susceptibility, the plasma frequency , the magnetoresistance , and the ...
Charge carrier density, also known as carrier concentration, denotes the number of charge carriers per volume. In SI units, it is measured in m −3. As with any density, in principle it can depend on position. However, usually carrier concentration is given as a single number, and represents the average carrier density over the whole material.
In 1957, Bethe and Salpeter's book Quantum mechanics of one-and two-electron atoms [3] built on Hartree's units, which they called atomic units abbreviated "a.u.". They chose to use ℏ {\displaystyle \hbar } , their unit of action and angular momentum in place of Hartree's length as the base units.
Linear charge density (λ) is the quantity of charge per unit length, measured in coulombs per meter (C⋅m −1), at any point on a line charge distribution. Charge density can be either positive or negative, since electric charge can be either positive or negative. Like mass density, charge density can vary with position.
In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. [1] The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional area at a given point in space, its direction being that of the motion of the positive charges at this point.
The density of states related to volume V and N countable energy levels is defined as: = = (()). Because the smallest allowed change of momentum for a particle in a box of dimension and length is () = (/), the volume-related density of states for continuous energy levels is obtained in the limit as ():= (()), Here, is the spatial dimension of the considered system and the wave vector.
Under the free electron model, the electrons in a metal can be considered to form a uniform Fermi gas. The number density N / V {\displaystyle N/V} of conduction electrons in metals ranges between approximately 10 28 and 10 29 electrons per m 3 , which is also the typical density of atoms in ordinary solid matter.