6
ethylene D2h 
  C         -0.663800        0.000000        0.000000
  H         -1.236600       -0.923600        0.000000
  H         -1.236600        0.923600        0.000000
  C          0.663800        0.000000        0.000000
  H          1.236600        0.923600        0.000000
  H          1.236600       -0.923600        0.000000