I am newbie to DFT and I am trying to understand the different input parameters in the VASP POSCAR file of bulk silicon system, provided in the examples here. I am trying to find the lattice constant of Silicon. My question is the following:
Do I need to know the lattice structure of silicon beforehand to perform this calculation? Can't I give a different unit cell structure (lines 3, 4 and 5 in the link) and still arrive at the same lattice constant?