config.cif. Supercell: 1 x 1 x 1                                                
         0         3
         20.00000000          0.00000000          0.00000000
          0.00000000         20.00000000          0.00000000
          0.00000000          0.00000000         20.00000000
Ar               1
        -10.00000000        -10.00000000        -10.00000000
B                2
         -7.50000000        -10.00000000        -10.00000000
B                3
        -10.00000000         -5.00000000        -10.00000000
