MolMod2:ekm
NH3 - Ammonia
Summary
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Final Energy: -56.44397188 a.u.
Point Group: C3V
RMS Gradient: 0.00000485 a.u.
N-H Bond Length: 1.01798Å
H-N-H Bond Angle: 105.741°
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
A Jmol dynamic image of an optimised ammonia molecule |
Vibrations of NH3
- From the 3N-6 rule we would expect a total of 6 modes of vibration.
- 2 pairs of the modes are degenerate.
- There are 3 "bending" vibrations and 3 "stretching" vibrations.
- Mode 4 is highly symmetric.
- Mode 1 is the umbrella mode.
- 2 bands would be expected in an experimental spectrum of gaseous ammonia.
Charge Distribution
We would expect there to be a positive charge on the hydrogen atoms, and a negative charge on the nitrogen atom. This is because nitrogen is more electronegative than hydrogen, and therefore will draw electron density towards itself.
N charge: -1.125
H charge: +0.375
N2 - Nitrogen
Summary
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Final Energy: -109.52412868 a.u.
Point Group: D*H
RMS Gradient: 0.00000060 a.u.
N-N Bond Length: 1.09200Å
Bond Angle: 180°
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
A Jmol dynamic image of an optimised nitrogen molecule |
Vibrations of N2
- From the 3N-5 rule we would expect a total of 1 mode of vibration.
- There is 1 "stretching" vibration.
- No bands would be expected in an experimental spectrum of gaseous nitrogen.
Charge Distribution
We would expect there to be no overall charge on either nitrogen atom.
N charge: 0
H2 - Hydrogen
Summary
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Final Energy: -1.17853936 a.u.
Point Group: D*H
RMS Gradient: 0.00000017 a.u.
N-H Bond Length: 0.74279Å
Bond Angle: 180°
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
A Jmol dynamic image of an optimised hydrogen molecule |
Vibrations of H2
- From the 3N-5 rule we would expect a total of 1 modes of vibration.
- There is 1 "stretching" vibration.
- No bands would be expected in an experimental spectrum of gaseous nitrogen.
Charge Distribution
We would expect there to be no overall charge on either hydrogen atom.
H charge: 0
Reaction Energies
E(NH3): -56.443972 a.u.
2xE(NH3): -112.887944 a.u.
E(N2): -109.524129 a.u.
E(H2): -1.178539 a.u.
3xE(H2): -3.535618 a.u.
ΔE = 2xE(NH3) - [E(N2) + 3xE(H2)]: -0.0557907 a.u.
ΔE: -146.48 kJ mol-1
Since ΔE is positive, the reaction is endothermic. This suggests that the gaseous reactants are more stable than the product.
CF4 - Carbon Tetrafluoride
Summary
Calculation Method: RB3LYP
Basis Set: 6-31G(d,p)
Final Energy: -437.47627267
Point Group: TD
RMS Gradient: 0.00004048
C-F Bond Length: 1.32939 Å
F-C-F Bond Angle: 109.471°
Item Value Threshold Converged? Maximum Force 0.000078 0.000450 YES RMS Force 0.000042 0.000300 YES Maximum Displacement 0.000133 0.001800 YES RMS Displacement 0.000071 0.001200 YES
A Jmol dynamic image of an optimised carbon tetrafluoride molecule |
Vibrations of CF4
- From the 3N-6 rule, we would expect 9 modes of vibration.
- 1 pair of modes are degenerate, and 2 groups of 3 modes are degenerate.
- 8 modes are "bending" modes,and 1 is "stretching" modes.
- Mode 6 is highly symmetric.
- I would expect to see 1 band in an experimental spectrum of gaseous tetrafluoromethane.
Charge Distribution
We would expect there to be a strong positive charge on the carbon atom and negative charges on the fluorine atoms, owing to fluorine's strong electronegativity, resulting in electrongs being drawn away from the carbon nucleus to the fluorine nuclei.
Charge on C: +1.407
Charge on F: -0.352
Molecular Orbitals
- The 8th molecular orbital is deep in energy and is occupied.
-The 16th molecular orbital is in the HOMO/LUMO energy region and is occupied.
-The 24th molecular orbital is high in energy and is unoccupied.