Why is the volume of FCC and BCC different in reciprocal space?

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The discussion addresses the differences in volume between BCC and FCC structures in reciprocal space. In real space, BCC has a total of 2 atoms per unit cell, while FCC has 4 atoms. When transformed to reciprocal space, BCC becomes an FCC structure with a volume of 4 times the cubic lattice length, while FCC transforms into a BCC structure with a volume of 2 times the cubic lattice length. The confusion arises regarding the correct volume calculations in reciprocal space, particularly the factors of 4 and 2. The magnitude of the unit vectors for the reciprocal lattice is also questioned, indicating a need for clarification on the dimensions involved.
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Taken from http://dao.mit.edu/8.231/BZandRL.pdf

BCC

In real space, it has a simple cubic lattice with one basis in the centre. Total number of atoms per unit cell = 2. Volume of primitive unit cell is then ##\frac{1}{2}a^3##.

In reciprocal space, BCC becomes an FCC structure. It has a simple cubic lattice of length ##\frac{2\pi}{a}## with 4 atoms in total. Why is the total volume then ##4 \left(\frac{2\pi}{a}\right)^3## and not ##\frac{1}{4}\left(\frac{2\pi}{a}\right)^3##?
FCC
In real space, it has a simple cubic lattic with 3 basis. Total number of atoms per unit cell = 4. Volume of primitive unit cell is then ##\frac{1}{4}a^3##.

In reciprocal space, FCC becomes a BCC structure. It has a simple cubic lattice of length ##\frac{2\pi}{a}## with 2 atoms in total. Why is the total volume then ##2 \left(\frac{2\pi}{a}\right)^3## and not ##\frac{1}{2}\left(\frac{2\pi}{a}\right)^3##?
 
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What is the the magnitude of the unit vectors of the reciprocal lattice? I don't think the size of the reciprocal cube for BCC is 2pi/a.
 
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