Schwartzite P with 4 unit cells

Finally, thanks for Chuang's effort, now we have this amazing P-type Schwartzite that contains four unit cells. With this model, we can see very clearly the detailed structures of four unit cells connected by necks with negative Gaussian curvatures. The neck is in fact the inner-rim of a D4h torus bearing a strong resemblance to the type V torus which has the D5h symmetry.