Atomization energy

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

Please look at the script ../../tutorials/N2.py:

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

First, an Atoms object containing one nitrogen is created and a fast EMT calculator is attached to it simply as an argument.

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

The total energy for the isolated atom is then calculated and stored in the e_atom variable.

e_atom = atom.get_potential_energy()

The molecule object is defined, holding the nitrogen molecule at the experimental bond length d=1.1 Angstrom.

d = 1.1
molecule = Atoms('2N', [(0.0, 0.0, 0.0), (0.0, 0.0, d)])

The EMT calculator is then attached to the molecule and the total energy is extracted into the e_molecule variable.

molecule.calc = EMT()
e_molecule = molecule.get_potential_energy()

The atomization energy is the energy required to break the bond, meaning that it is the negative energetic difference between the molecule and twice the single atom’s energy.

e_atomization = -1.0 * (e_molecule - 2 * e_atom)

Finally we print the relevant energies:

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

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