How can I distinguish degeneracy from band structure?

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    Degeneracy Valence band
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SUMMARY

Degeneracy in band structure occurs when energy bands cross or touch at the gamma point, indicating that multiple states share the same energy level. Specifically, conduction bands are considered degenerate at the gamma point due to their coalescence, while valence bands can cross without indicating degeneracy if they are separated by a band gap. The distinction between degeneracy and crossing is crucial; degeneracy requires energy levels to coincide, whereas crossing can occur without degeneracy if bands are not overlapping.

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  • Knowledge of the gamma point in Brillouin zones
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Mohammad-gl
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I have a band structure plot and want to know if it is degenerated or non-degenerated. How can I realize that?
This is the band structure.
Untitled.png
 
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Where the bands cross or touch at the gamma point, they are degenerate.
 
Dr Transport said:
Where the bands cross or touch at the gamma point, they are degenerate.
In fact my question is that the degeneracy is related to cross the valence and the conduction band or that can be happen even in touching the valences or conduction bands too?
 
Mohammad-gl said:
In fact my question is that the degeneracy is related to cross the valence and the conduction band or that can be happen even in touching the valences or conduction bands too?
I don't understand your response. The conduction bands are degenerate at the gamma point because they coalesce. The valence bands cross at the gamma point, because they cross. the conduction and valance bands are not degenerate in this case because they are completely separated by the band gap, plain and simple.
 
Dr Transport said:
I don't understand your response. The conduction bands are degenerate at the gamma point because they coalesce. The valence bands cross at the gamma point, because they cross. the conduction and valance bands are not degenerate in this case because they are completely separated by the band gap, plain and simple.
I mean that generally can we call a band structure degenerate even if there be a cross in the valence bands? and is not crucial that valence and conduction bands cross each other?
 

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