Atomization energy

The following script will calculate the atomization energy of a nitrogen molecule:

from ase import Atoms
from ase.calculators.emt import EMT

atom = Atoms('N')
atom.calc = EMT()
e_atom = atom.get_potential_energy()

d = 1.1
molecule = Atoms('2N', [(0., 0., 0.), (0., 0., d)])
molecule.calc = EMT()
e_molecule = molecule.get_potential_energy()

e_atomization = e_molecule - 2 * e_atom

print('Nitrogen atom energy: %5.2f eV' % e_atom)
print('Nitrogen molecule energy: %5.2f eV' % e_molecule)
print('Atomization energy: %5.2f eV' % -e_atomization)

First, an Atoms object containing one nitrogen is created and a fast EMT calculator is attached to it simply as an argument. The total energy for the isolated atom is then calculated and stored in the e_atom variable.

The molecule object is defined, holding the nitrogen molecule at the experimental bond length. The EMT calculator is then attached to the molecule and the total energy is extracted into the e_molecule variable.

Running the script will produce the output:

Nitrogen atom energy:  5.10 eV
Nitrogen molecule energy:  0.44 eV
Atomization energy:  9.76 eV