Another help request

[John Chang]

In case you're curious, I'm studying for the Physics GRE - these are practice problems. There seems to be a lot the GRE covers that I never covered in undergrad - I'm "covering" it for the first time, now.

There's a figure of the lattice that I can't really paste, but here's a URL to one substantially similar -
http://en.wikipedia.org/wiki/Image:Cubic-body-centered.png

52. The conventional unit cell of a body-centered
cubic Bravais lattice is shown in the figure above.
The conventional cell has volume a3 . What is
the volume of the primitive unit cell?
(A) a^3/8
(B) a^3/4
(C) a^3/2
(D) a^3
(E) 2a^3


I'm not looking for the answer, although, how to get the answer is appreciated. What the heck is a "primitive unit cell"? I've done my own legwork on the internet but I can't seem to get a straight answer, or at least an answer that I can use.

 

[domi]

I'm not looking for the answer, although, how to get the answer is appreciated. What the heck is a "primitive unit cell"? I've done my own legwork on the internet but I can't seem to get a straight answer, or at least an answer that I can use.

A primitive or simple cubic structure contains *one* atom per cubic unit (atoms at the corners of the cube). So in the case of BCC...