Economdi
Comments
It's great that you have a working wiki—you did a good job. However, your answers could have been elaborated more thoroughly. If you have any queries or want more detailed feedback on your computational lab, please contact Prof. Hunt.
NH3 molecule
Calculation Data
| name of submitted log file | DPE_NH3_optimisation.log |
| molecule | NH3 |
| method | RB3LYP |
| basis set | 6-31G(d,p) |
| final energy | -56.557769 |
| RMS gradient | 1.53x10-07 |
| point group | C3v |
Item Table
Confirmation of convergence for forces and displacements
Item Value Threshold Converged? Maximum Force 0.000000 0.000015 YES RMS Force 0.000000 0.000010 YES Maximum Displacement 0.000003 0.000060 YES RMS Displacement 0.000001 0.000040 YES
Low Frequencies
Confirmation that a minimum and CoM motion is near zero
Low frequencies --- -11.5222 -11.4865 -0.0030 0.0245 0.1415 25.6160
Low frequencies --- 1089.6618 1694.1735 1694.1738
Optimised molecule image
Jmol rotateable molecule
logfile: Media:DPE_NH3_OPTIMISATION.LOG
optimised NH3
Important geometric parameters
optimised bond distance and angle for NH3
r(N-H)=1.02Â
θ (H-N-H)=106°
Frequency, Symmetry, and Intensity of Vibrations Table
| Mode # | 1 | 2 | 3 | 4 | 5 | 6 |
| Wavenumber (cm-1) | 1089 | 1694 | 1694 | 3461 | 3590 | 3590 |
| Symmetry | A1 | E | E | A1 | E | E |
| Intensity (arbitrary units) | 145 | 14 | 14 | 1 | 0 | 0 |
IR Vibrations Image
Charge Analysis Image
Image of NBO charges colour coded red for negative and green for positive with the charge range being ±1.125
 | 
|
Table of NH3 charges
| atom | charge |
| N | -1.13 |
| H | +0.38 |
Molecular Orbitals
| real 2a1 MO | LCAO MO |
 |
|
Project molecule N2F2
Calculation Data
| name of submitted log file | N2F2OPTIMISATIONDPE.log |
| molecule | N2F2 |
| method | RB3LYP |
| basis set | 6-31G(d,p) |
| final energy | -309.00835 |
| RMS gradient | 0.018487863 |
| point group | C2v |
Item Table
Confirmation of convergence for forces and displacements
Item Value Threshold Converged? Maximum Force 0.000001 0.000015 YES RMS Force 0.000000 0.000010 YES Maximum Displacement 0.000001 0.000060 YES RMS Displacement 0.000001 0.000040 YES
Low Frequencies
Confirmation that a minimum and CoM motion is near zero
Low frequencies --- -0.0015 -0.0012 -0.0010 3.2225 4.3532 5.1001
Low frequencies --- 347.8772 561.2472 771.6105
Optimised molecule image
Jmol rotateable molecule
logfile: Media:DPE_N2F2_optimisation.LOG
optimised N2F2
Important geometric parameters
optimised bond distance and angle for NH3
r(F-N)=1.28Â
r(N=N)=1.23Â
θ (F-N-N)=120°
θ (F-N-N-F)=0°
Frequency, Symmetry, and Intensity of Vibrations Table
| Mode # | 1 | 2 | 3 | 4 | 5 | 6 |
| Wavenumber (cm-1) | 348 | 561 | 772 | 949 | 987 | 1637 |
| Symmetry | A1 | A2 | B2 | A1 | B2 | A1 |
| Intensity (arbitrary units) | 1 | 0 | 75 | 75 | 81 | 21 |
IR Vibrations Image
How many vibrations are expected from the 3N-6 rule?
N=4 (4 atoms)
3N-6
=3x(4)-6
=6
6 vibrations should be observed
Why are there only 4 peaks in the IR spectrum?
There are only four peaks visible in the IR due to the intensity of the vibrations. The vibrations at 348cm-1 and 561cm-1 have nearly 0 or 0 intensity hence peaks on the IR cannot be observed.
Which vibration is the asymmetric N-F stretch?
Vibration 3 is the asymmetric N-F stretch at 772cm-1 this is because as one F atom gets closer to the N atom the other F does the opposite and get further and vice versa. The N atoms stay the same.
What is the nature of the highest energy vibration?
The nature of the highest energy vibration is the F atoms have no part and the N atoms are symmetrically expanding and contracting (stretching) from each other.
Charge Analysis Image
Image of NBO charges colour coded red for negative and green for positive with the charge range being ±0.215
 | 
|
Table of N2F2 charges
| atom | charge |
| N | +0.22 |
| F | -0.22 |
The molecule from the log file does not have bonds between the F and N atoms, what is going on here?
This is due to the computer having its own processing functions as to which it makes it unable for us to visually see the bonds however they are still here.
Molecular Orbitals
| Real MO 9 | LCAO Diagram of MO 9 |
 |
|
Which MOs are core orbital MOs?
The MO's that are the core orbitals are MO 1-4. This is because they are the lowest in energy and are the s orbitals that do not have any play in merging.
