Further, the shortest distance of the tetragonal face from the center of the zone is
d S ¼
p
2
The above calculations provide us
p
2
\k F \p
This shows that the Fermi sphere does not remain within the first B-Z.
Multiple Choice Questions (MCQ)
1. The shape of the Wigner–Seitz unit cell of a square lattice is:
(a) Rectangle
(b) Triangular
(c) Square
(d) Hexagonal
2. The shape of the Wigner–Seitz unit cell of a hexagonal lattice (in 2-D) is:
(a) Rectangle
(b) Triangular
(c) Square
(d) Hexagonal
3. The shape of the Wigner–Seitz unit cell of a simple cubic lattice is:
(a) Tetrahedral
(b) Octahedral
(c) Cubic
(d) Hexagonal
4. The shape of the Wigner–Seitz unit cell of a body-centered cubic lattice is:
(a) Tetrahedral
(b) Rhombic dodecahedral
(c) Cubic
(d) Truncated octahedral
5. The shape of the Wigner–Seitz unit cell of a face-centered cubic lattice is:
(a) Tetrahedral
(b) Rhombic dodecahedral
(c) Cubic
(d) Truncated octahedral
2.4 Fermi Surface and Brillouin Zone
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