# Set up elements and positions
elm = [ Oxygen, Hydrogen, Hydrogen ]         
pos = [[ 0.000, 0.000, 0.0],
       [ 0.757, 0.586, 0.0],
       [-0.757, 0.586, 0.0]]*Angstrom

# Add them to a configuration
h2o = MoleculeConfiguration(elm, pos)