Hello!
I am trying to understand the volume formula for the truncated octahedron which is according to http://mathworld.wolfram.com/TruncatedOctahedron.html
V=8*sqrt(2)*a**3
where "a" is the length of an edge. The distance "b" between two quadratic faces is
b=2*sqrt(2)*a
also:
V=b**3/2

The crystl.doc file says:
Quote:


OCTAhedral - a = b = c, alpha = beta = gamma = 109.4712206344907
(a.k.a truncated octahedron)
(example: 40.0 40.0 40.0 109.471220634 109.471220634 109.471220634 )
(volume = 4*sqrt(3))/9 * a**3 )
(truncated cube length = a * sqrt(4/3) )
(degrees of freedom = 1)




Here, the distance "b" between two quadratic faces, called truncated cube length in the doc, is
b=a*sqrt(4/3)
Also here:
V=b**3/2

When charmm sets up a truncated octahedron from a cubic box it obviously rotates the whole system, ie. the atoms or does it rotate only the truncated octahedron within the cubic box leaving out the atoms and thus reduces the resulting edge length and volume?

Thanks for any help.