O atom in a box
 1.0          ! universal scaling parameters
 8.0 0.0 0.0  ! lattice vector  a(1)
 0.0 8.0 0.0  ! lattice vector  a(2)
 0.0 0.0 8.0  ! lattice vector  a(3)
1 1           ! number of atoms for each species
sel           ! selective degrees of freedom are changed
cart          ! positions in cartesian coordinates
 0 0 0       F F T  ! first atom
 0 0 1.143   F F T  ! second atom
