Although one must pay attention to the fact how to select Muffin-Tin (MT) sphere radii as indicated in the frequently asked question (FAQ) of the WIEN2k code, we can neglect it for our current purpose. We also in this practice, where we only focus to understand the expression of "Crystal = Lattice + Basis", not worry about correct experimental value of lattice parameters and the symmetry of the system.
Practice:
2. Now change the P to FCC and try again
3. Now change the FCC to B and try gain