LAMMPS 'data.' description 

       3 atoms
       2 bonds
       1 angles

       2 atom types
       1 bond types
       1 angle types

    0.0 20.1      xlo xhi
    0.0 20.1      ylo yhi
    0.0 20.1      zlo zhi

 Masses

 1 1.008 # H
 2 15.9994 # O

Atoms

      1    1  2 -0.830    1.55000    1.55000    1.50000
      2    1  1  0.415    1.55000    2.30695    2.08588
      3    1  1  0.415     1.55000    0.79305    2.08588

Bonds

      1   1      1      2
      2   1      1      3

Angles

      1   1      2      1      3