Mesh generation

I have a big problem with meshing.

For a thermo-mechanical problem i have to assign
periodic boundary conditions. To do that i need exactly the same number
of nodes on parallel faces (like bottom-node (X,Y,0) = top-node (X,Y,Z) .
Unfortunately ABAQUS doesn't´t mesh like this. I have  a cube (Object)
with face centered grains (see the attached picture) but after meshing
the nodes are not at the same opposite side. Can anybody help me with
this problem? Or any suggestions?

Thanks 

Christoph