Local-density approximation: Difference between revisions

Revision as of 22:59, 24 March 2006

Revision as of 02:56, 27 April 2006

Line 3:

The basic theorem of [[Density Functional Theory]] states that the energy of a system of electrons is a[[functional (mathematics) | functional ]] of the [[electronic density]], in particular the exchange and correlation energy is also a functional of the density (this energy can be seen as the quantum part of the electron-electron interaction). This XC functional is not known exactly and must be approximated.

LDA is the most simple approximation for this functional, it is ''local'' in the sense that the the electron exchange and correlation energy at any point of the space is a function of the electron density at that point in space only.

The LDA functional is derived from a model assuming that the per-electron exchange-correlation energy at every point in space is equal to the per-electron exchange-correlation energy of a homogeneous electron gas. This model is sometimes known as the [[Jellium]] model.