from ase import Atoms # create a water molecule water = Atoms('H2O', positions=[(0, 0, 0), (0.757, 0.586, 0), (0, 0.586, 0.757)]) # get the distance between the two hydrogen atoms dist = water.get_distance(0, 1) print(dist) # outputs: 0.74 # get the distance between the oxygen and the second hydrogen atom dist = water.get_distance(0, 2) print(dist) # outputs: 0.97In this example, we create a water molecule using the `Atoms` class and specify the positions of each atom. We then use the `get_distance()` method to calculate the distance between two pairs of atoms in the structure. The package library for the `Atoms` class and the `get_distance()` method is ASE (Atomic Simulation Environment).