Re: [math-fun] A family of lattices including both FCC, BCC, and a new(?) lattice

I guess this depends on how we define nearest neighbors. I would not define this as the number of neighbors that are tied for the shortest distance to a given point. Rather, I'd define it as the number of faces that the Voronoi region of a point has. In the case of BCC, the Voronoi region is the Archimedean solid called the truncated octahedron, which has 14 faces. --Dan On 2013-02-05, at 2:34 PM, Warren Smith wrote:

BCC: arises when a=c=1. Sphere packing volume-density = pi*sqrt(3)/8 = 0.6801747619 #nearest neighbors = 8