1     6  TIP3F Water Dimer
2     1  O      0.000000    0.000000    0.000000     1     2     3
3     2  H     -0.974993    0.000000   -0.034654     2     1
4     3  H      0.163320   -0.000001    0.942147     2     1
5     4  O     -2.728343    0.000000    0.090156     1     5     6
6     5  H     -3.290938    0.753669   -0.106597     2     4
7     6  H     -3.290938   -0.753669   -0.106598     2     4
8