How to show all Brillouin zones have same volume

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    Brillouin Volume
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Discussion Overview

The discussion revolves around the volume of Brillouin zones in both 2D and 3D lattices, specifically addressing the claim that all Brillouin zones have the same volume. Participants explore calculations and seek proofs for this assertion, while also addressing potential errors in their approaches.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant calculates the volume of the first Brillouin zone as (2pi)^3/V, where V is the volume of a unit cell, and notes the common assertion that all Brillouin zones share this volume.
  • Another participant states that the volume of the reciprocal cell is defined as 1/V, referencing the direct cell volume.
  • Further clarification is provided on the definitions of reciprocal lattice vectors and their relation to the volume of the direct lattice cell.
  • The initial poster expresses confusion over their calculations, finding that the first and second Brillouin zones appear to have the same volume, but the third zone seems to have double that volume.
  • Another participant suggests that the initial poster may have included areas not belonging to the third Brillouin zone in their calculations and asks for details on how the calculations were performed.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the volume of the Brillouin zones, as there are conflicting calculations and interpretations of the definitions involved. The discussion remains unresolved regarding the proof of equal volumes across all Brillouin zones.

Contextual Notes

There are potential limitations in the calculations presented, including assumptions about the areas included in the calculations and the definitions of the reciprocal lattice vectors. The discussion does not clarify these aspects fully.

aleeds
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It is quite easy to calculate the volume of the first brillouin zone to be (2pi)^3/V if V is the volume of a unit cell in the real lattice. In many places one can also find the statement that all Brillouin zones have the same volume. I have not however found a proof of this anywhere. The 3D case seemed complicated so I first tried solving hte problem for the 2D case but must have done something wrong as I found that the first and second Brillouin zones have the same volume (or area in the 2D case) but then for the 3rd Brillouin zone I foudn it to be twice of this. Does anybody know a solution to this (either in 2D or even better in 3D)?
Thanks
 
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By its definition the volume of the reciprocal cell is 1/V, where V is the direct cell volume. V=(a.[bc])
 
Sorry, it comes from the definition a*=[b x c]/V, b*= [c x a]/V, ...
 
aleeds said:
It is quite easy to calculate the volume of the first brillouin zone to be (2pi)^3/V if V is the volume of a unit cell in the real lattice. In many places one can also find the statement that all Brillouin zones have the same volume. I have not however found a proof of this anywhere. The 3D case seemed complicated so I first tried solving hte problem for the 2D case but must have done something wrong as I found that the first and second Brillouin zones have the same volume (or area in the 2D case) but then for the 3rd Brillouin zone I foudn it to be twice of this. Does anybody know a solution to this (either in 2D or even better in 3D)?
Thanks
It may be that you include areas which does not belong to the third zone.
How did you do the calculation?
 

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