VASP Input files: POSCAR

The POSCAR file contains the positions of the ions. For the fcc Al example, the POSCAR file contains the following lines only:

Al_FCC # comment line
1 # universal scaling factor
4.00 0.00 0.00 # first Bravais lattice vector
0.00 4.00 0.00 # second Bravais lattice vector
0.00 0.00 4.00 # third Bravais lattice vector
4 # number of atoms per species, be consistent:
direct or cartesian, only first letter is significant
0.00000000 0.00000000 0.0000000 positions
0.50000000 0.00000000 0.5000000
0.50000000 0.50000000 0.0000000
0.00000000 0.50000000 0.5000000

The positions can be given in direct (fractional) or Cartesian coordinates. In the second case, positions will be scaled by the universal scaling factor given in the second line. The lattice vectors are always scaled by the universal scaling factor. File is free formatted. Note that strings after # sign are just to explain the purpose of the string.