Callagalex1
Contents
lab marking
You have a good working wiki. Your reported RMS and energy values are incorrect in method information for NH3 molecule. It would be good if you round off reported values to correct significant figures. If you have any specific questions, do email Prof. Hunt
NH3 molecule
Calculation Data
| name of submitted log file | AGRC_NH3_OPTIMISATION.LOG |
| molecule | NH3 |
| Method | RB3LYP |
| Basis Set | 6-31G(d,p) |
| Final Energy | -56.557769 |
| RMS Gradient | 0.000000 |
| Point Group | C3V |
Item Table
Optimised Molecule Image
Jmol Rotatable File
Logfile: Media:AGRC_NH3_OPTIMISATION.LOG
Optimised NH |
Important Geometric Parameters
Optimised bond distance and angle for NH3molecule:
| coord | value |
| r(N-H) | 1.02Â |
| θ(H-N-H) | 105° |
Vibrations
| Mode | Wavenumber (cm-1) | Intensity | Symmetry |
| 1 | 1089 | 145 | A1 |
| 2 | 1694 | 14 | E |
| 3 | 1694 | 14 | E |
| 4 | 3461 | 1 | A1 |
| 5 | 3590 | 0.2 | E |
| 6 | 3590 | 0.2 | E |
Gaussview Infrared Spectrum
Frequencies
Low frequencies --- -5.6864 -3.6131 -3.6124 0.0017 0.0048 0.0162 Low frequencies --- 1089.3674 1693.9284 1693.9284
Charges
Images of the NBO charges (colour coded red for negative and dark green for positive), and overall the charge range (±1.125e)
table of NH3 charges:
| atom | charge |
|---|---|
| N | -1.13 |
| H | +0.38 |
Molecular Orbital Images
| the real 2a1 MO | the LCAO MO |
|---|---|
 |
|
N2F2 molecule
Calculation Data
| name of submitted log file | Agrc_Nh3_item_table |
| molecule | N2F2 |
| Method | RB3LYP |
| Basis Set | 6-31G(d,p) |
| Final Energy | -308.9972 |
| RMS Gradient | 0.041752789 |
| Point Group | C2V |
Item Table
Optimised Molecule Image
Jmol Rotatable File
Logfile: Media:AGRC_N2F2_OPTIMISATION.LOG
Optimised NH |
Important Geometric Parameters
Optimised bond distance and angle for NH3molecule:
| coord | value |
| r(N-F) | 1.40Â |
| θ(F-N-F) | 114° |
Vibrations
| Mode | Wavenumber (cm-1) | Intensity | Symmetry |
| 1 | 349 | 0.6 | A1 |
| 2 | 562 | 0 | A2 |
| 3 | 772 | 74 | B2 |
| 4 | 951 | 75 | A1 |
| 5 | 988 | 81 | B2 |
| 6 | 1634 | 20 | A1 |
Gaussview Infrared Spectrum
Frequencies
Low frequencies --- -11.6302 -0.0013 -0.0013 0.0007 5.6017 9.2756 Low frequencies --- 348.5581 561.7116 772.3042
Charges
Images of the NBO charges (colour coded red for negative and dark green for positive), and overall the charge range (±1.125e)
table of NH3 charges:
| atom | charge |
|---|---|
| N | 0.22 |
| H | -0.22 |
Molecular Orbital Images
| the real 9 MO | the LCAO MO |
|---|---|
 |
|
Provided Questions
- The molecule from the log file does not have bonds between the F and N atoms, what is going on here?
- Gaussview has a preset bond length where it displays a bond, the fact that there was no bond was shown just tells us that whilst a bond exists, it is longer than the preset gaussview length
- How many vibrations are expected from the 3N-6 rule?
- 3 x 4 - 6 = 6 vibrational modes
- Why are there only 4 peaks in the IR spectrum?
- Modes 1 and 2 have 0.6 and 0 intensity respectively, resulting in the two not showing up on the IR spectrum
- Which vibration is the asymmetric N-F stretch?
- Vibrational mode 3 at an energy of 772cm-1
- What is the nature of the highest energy vibration?
- N=N symmetric stretch
- Which MOs are core orbital MOs?
- For Flourine the core S orbitals are MOs 1 & 2, for Nitrogen the core S orbitals are MOs 3 & 4
