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A perturbative model of electrons moving in a weak lattice-periodic potential. Bragg mixing opens gaps near degeneracies, while states far from those surfaces remain close to free-electron states.
wp-physics-nearly-free-electrontong-solid-state-physicsmit-theory-of-solidsEach relation below ends at this concept.
This is an authored directed relation from the source endpoint to the target endpoint.
When the periodic potential is weak relative to the free-electron kinetic scale, perturbation theory recovers nearly free dispersion away from Bragg degeneracies and controlled gap opening after degenerate perturbation theory.
The target is recovered from the source either in a stated mathematical or asymptotic limit, or through a quantitatively controlled approximation with identified small parameters or omitted terms. The edge label and detail must state which case applies and its regime of validity.
wp-physics-nearly-free-electronwp-physics-band-structuretong-solid-state-physicsEach relation below starts at this concept.
This is an authored directed relation from the source endpoint to the target endpoint.
The nearly-free approximation produces bands close to the free-electron parabola, with gaps opened where reciprocal-lattice scattering mixes degenerate plane waves.
The target represents a state, property, observable, or state-dependent description associated with the source system or theory.
wp-physics-nearly-free-electronwp-physics-band-structuretong-solid-state-physics