6
Graphene fragment (hexagon)
C        0.0000    0.0000    0.0000
C        1.4200    0.0000    0.0000
C        2.1300    1.2300    0.0000
C        1.4200    2.4600    0.0000
C        0.0000    2.4600    0.0000
C       -0.7100    1.2300    0.0000
