Free electron model
From Biocrawler, the free encyclopedia.
In physics, the free electron model is a possible model for the behaviour of electrons in a crystal structure. The core idea is that the valence electrons detach themselves completely from their ions and form an "electron gas".
While this model is the simplest model, it reproduces the main electronic properties of metals. The two fundamental asumptions are:
- the independent electron approximation that considers the electrons as independent. Electron screening is one justification for ignoring electron-electron interactions.
- the electrons move in a constant energy potential (the structure of the material is completely ignored). The Bloch theorem states that a periodic potential (such as a regular array of atoms) cannot scatter a travelling wave electron.
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Predictions of the model
This very simple model of metals more or less correctly predicts:
- the shape of the electronic density of states.
- the range of binding energy values.
- the heat capacity functional form.
- electrical conductivities.
- the Weidemann-Franz law.
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