A one-dimensional crystal of lattice dimension 'a' is metallic. If the structure is distorted in such a way that the lattice dimension is enhanced to '2a'.
(a)The electronic structure remains unchanged.
(b)The width of conduction band decreases and a band gap is generated.
(c)The width of conduction band increases
(d)The width of the conduction band remains unchanged
Answer
Answer: B ✓ checked by 4AB · confidence high
Explanation
Doubling the period (Peierls distortion) halves the Brillouin zone: the half-filled band splits at the new zone boundary, the conduction band narrows and a gap opens — the metal becomes a semiconductor/insulator.