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Nearly free electron approximation band structure

A consequence of the cancellation between the two terms of (6.47) is the surprisingly good description of the electronic structure of solids given by the nearly-free electron approximation. The fact that many metal and semiconductor band structures are a small distortion of the free electron gas band structure suggests that the valence electrons do indeed feel a weak potential. The Phillips and Kleinman potential explains the reason for this cancellation. [Pg.231]

In practice, the true crystal potential does not satisfy the criterion for the applicability of the nearly-free-electron approximation, but there are much weaker equivalent potentials, or pseudopotentials, which do. By equivalent we mean that they produce the same band structure for the valence and conduction bands (but not necessarily the same wave functions). The difference is that the potential must of necessity be strong enough to bind states at lower energies (core states, more or less) but the pseudopotential need not. The elimination of such bound states produces a potential which is much weaker in the region close to the ion cores. This cancellation of the strong inner part of the potential can be seen from many points of view but will here be accepted as a fact of life for s-p-bonded systems. [Pg.60]


See other pages where Nearly free electron approximation band structure is mentioned: [Pg.402]    [Pg.79]    [Pg.188]    [Pg.120]    [Pg.407]    [Pg.2]    [Pg.302]    [Pg.182]    [Pg.10]    [Pg.355]    [Pg.312]    [Pg.15]    [Pg.52]    [Pg.258]    [Pg.216]    [Pg.365]    [Pg.704]    [Pg.249]    [Pg.239]    [Pg.306]    [Pg.101]    [Pg.231]    [Pg.350]   


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