Question

Group analysis forbids band-crossing in 1D in terms of conventional band theory. I read this in a good solid state physics book. But there's no explanation at all. Can anyone help on this?

This post imported from StackExchange Physics at 2014-08-22 05:05 (UCT), posted by SE-user huotuichang

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Minor comment to the post (v3): Please consider to mention explicitly author, title, etc. of link, so it is possible to reconstruct link in case of link rot.

This post imported from StackExchange Physics at 2014-08-22 05:05 (UCT), posted by SE-user Qmechanic

Answer 1

I don't know whether the following explanation is relevant for your question:

Generally speaking, according to the von Neumann-Wigner theorem (no-crossing theorem), for a band structure, the band-crossing usually happens in 3D system. But there is also possibility for the so-called accidental degeneracy in low dimensions which may result from symmetry.

This post imported from StackExchange Physics at 2014-08-22 05:05 (UCT), posted by SE-user K-boy