Search results
Results from the WOW.Com Content Network
In solid-state physics, the free electron model is a quantum mechanical model for the behaviour of charge carriers in a metallic solid. It was developed in 1927, [1] principally by Arnold Sommerfeld, who combined the classical Drude model with quantum mechanical Fermi–Dirac statistics and hence it is also known as the Drude–Sommerfeld model.
Electrical conduction of metals is a well-known phenomenon and is attributed to the free conduction electrons, which can be measured as sketched in the figure. The current density j is observed to be proportional to the applied electric field and follows Ohm's law where the prefactor is the specific electrical conductivity .
Drude applied the kinetic theory of a dilute gas, despite the high densities, therefore ignoring electron–electron and electron–ion interactions aside from collisions. [ Ashcroft & Mermin 13 ] The Drude model considers the metal to be formed of a collection of positively charged ions from which a number of "free electrons" were detached.
The alkali metals are expected to have the best agreement with the free electron model since these metals only one s-electron outside a closed shell. However even sodium, which is considered to be the closest to a free electron metal, is determined to have a more than 25 per cent higher than expected from the theory.
Dispersion relation for the 2D nearly free electron model as a function of the underlying crystalline structure. The nearly free electron model is a modification of the free-electron gas model which includes a weak periodic perturbation meant to model the interaction between the conduction electrons and the ions in a crystalline solid.
[1]: 161 The first one is the nearly free electron model, in which the electrons are assumed to move almost freely within the material. In this model, the electronic states resemble free electron plane waves, and are only slightly perturbed by the crystal lattice. This model explains the origin of the electronic dispersion relation, but the ...
Metallic bonding is a type of chemical bonding that arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It may be described as the sharing of free electrons among a structure of positively charged ions .
The Drude Theory of Metals; The Sommerfeld Theory of Metals; Failures of the Free Electron Model; Crystal Lattices; The Reciprocal lattice; Determination of Crystal Structures by X-Ray Diffraction; Classification of Bravais Lattices and Crystal Structures; Electron Levels in a Periodic Potential: General Properties; Electrons in a Weak Periodic ...