Local-density approximation: Difference between revisions

Revision as of 09:56, 15 February 2007

Revision as of 03:14, 18 March 2007

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The Hohenberg-Kohn theorem states that the energy of the [[Stationary state|ground state]] of a system of electrons is a [[Functional (mathematics)|functional]] of the [[Electronic density|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 simplesimplest approximation for this functional, it is ''local'' in the sense that the electron exchange and correlation energy at any point of thein space is a function of the electron density at that point in space only.

The LDA functional assumes 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.