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NH3 molecule

Calculation Method: RB3LYP

Basis Set: 6-31G(d.p)

Final Energy (E(RB3LYP)): -56.55776873 a.u.

Point Group: C3V

        Item               Value     Threshold  Converged?
 Maximum Force            0.000004     0.000450     YES
 RMS     Force            0.000004     0.000300     YES
 Maximum Displacement     0.000072     0.001800     YES
 RMS     Displacement     0.000035     0.001200     YES
Ammonia Molecule

The optimisation file is liked to here

Vibrational Modes


Expect 6 modes from the 3N-6 rule

Nodes number 2 and 3 are degenerate, and modes 5 and 6 are degenerate.

Bending vibrations:1, 2, 3 Stretching Vibrations: 4,5,6

Mode 4 is highly symmetric and there is an umbrella mode which is mode 1

In the IR spectrum you should expect to see 2 bands. 2 of the degenerate stretches and one other bend modes cause no overall change in dipole moment so wont show on the spectrum.

Charges

You would expect Nitrogen to have the negative charge
as it is the more electronegative atom so draws electron
density towards itself.

H2

Optimisation

Calculation Method: RB3LYP

Basis Set: 6-31G(d.p)

Final Energy E(RB3LYP): -1.17853936au

Point Group: D*H

         Item               Value     Threshold  Converged?
 Maximum Force            0.000000     0.000450     YES
 RMS     Force            0.000000     0.000300     YES
 Maximum Displacement     0.000000     0.001800     YES
 RMS     Displacement     0.000001     0.001200     YES
Hydrogen Molecule

The optimisation file is liked to here

Vibrational Modes


It's a linear molecule so the 3N-5 rule is used, Expext 1 vibrational mode.

The mode is a stretch, and there's no dipole moment so no peaks will show up on the IR spectrum.

Charges

N2

Calculation Method: RB3LYP

Basis Set: 6-31G(d.p)

Final Energy E(RB3LYP): -109.52412868 au

Point Group: D*H

        Item               Value     Threshold  Converged?
 Maximum Force            0.000001     0.000450     YES
 RMS     Force            0.000001     0.000300     YES
 Maximum Displacement     0.000000     0.001800     YES
 RMS     Displacement     0.000000     0.001200     YES
Nitrogen Molecule

The optimisation file is liked to here

Vibrational Modes

Only 1 vibrational mode, the mode is a stretch. Linear so use the 3N-5 Rule, therefore only one mode expected.

No dipole moment so no bands would be visible on spectrum.

Charges

Energy

E(NH3)= -56.55776873au

2*E(NH3)= -113.1155375au

E(N2)= -109.52412868au

E(H2)= -1.17853936au

3*E(H2)= -3.53561808au

dE=2*E(NH3)-[E(N2)+3*E(H2)]= -0.05579074au

in kj/mol: -146.479KJ/mol

The more stable side of the reaction is the ammonia product as there is a decreases in energy so NH3 molecule has less E.

Literature Energy Change Value -45.8 KJ/mol

Source: https://en.wikipedia.org/wiki/Haber_process

O2

Calculation Method: RB3LYP

Basis Set: 6-31G(d.p)

Energy E(RB3LYP): -150.25742434au

Point Group: D*H

         Item               Value     Threshold  Converged?
 Maximum Force            0.000130     0.000450     YES
 RMS     Force            0.000130     0.000300     YES
 Maximum Displacement     0.000080     0.001800     YES
 RMS     Displacement     0.000113     0.001200     YES
Oxygen Molecule

The optimisation file is liked to here

Vibrational Modes

Will see no bands in the IR spectrum as there is only one vibrational mode which is a stretch and it causes no change in dipole moment.

Charges

Molecular Orbitals

This shows the bonding molecular orbital made up of 2 pi 2px orbitals overlapping.

This is an anti-bonding molecular orbital, made up of the 2 pi2pz atomic orbitals out of phase.

This is the HOMO as all the molecular orbitals with higher energy contain no electrons. It is made up of anti-bonding pi 2px atomic orbitals.

This is the LUMO, the lowest energy molecular orbital which contains no electrons. It's the anti-bonding molecular orbital made up of pi 2py atomic orbitals on the 2 O atoms.

This is the sigma 2pz MO made of the oxygen atoms bonding pi 2pz atomic orbitals.