Thompshann4

Lab1 Marking

You did a great job especially with the formatting. However, a wavenumber was rounded incorrectly, and you have reported wrong energy, RMS gradient, and geometric parameters. If you have any queries, please contact Prof. Hunt.

NH₃ Molecule

calculation data

Name of submitted log file	HTHOMPSON_NH3_OPTF_POP.LOG
Molecule	NH3
Method	RB3LYP
Basis set	6-31G(d,p)
Final energy	-56.556405
RMS gradient	0.0098
Point group	C3V

Item Table

         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 ---   -5.6864   -3.6131   -3.6124    0.0017    0.0048    0.0162
 Low frequencies --- 1089.3674 1693.9284 1693.9284

Optimised molecule image

Jmol rotateable molecule

logfile: Media:HTHOMPSON_NH3_OPTF_POP.LOG

Optimised NH molecule

Important geometric parameters

Optimised bond distance and angle for NH₃
r(N-H)=1.02Â
θ(H-N-H)=106°

Vibrations

Mode	1	2	3	4	5	6
Wavenumber (cm-1)	1090	1694	1694	3461	3590	3590
Symmetry	A1	E	E	A1	E	E
Intensity (arbitary units)	145	14	14	1	0	0

IR Spectra

Atomic charges

Charges of each atom

N	-1.13
H	+0.38

Molecular Orbital Diagram

Project Molecule

Calculation Data

Name of submitted log file	HThompson_N2F2_optf_pop.LOG
Molecule	N2F2
Method	RB3LYP
Basis set	6-31G(d,p)
Final energy	-309.012413
RMS gradient	0.000001
Point group	C2V

Item Table

         Item               Value     Threshold  Converged?
 Maximum Force            0.000002     0.000015     YES
 RMS     Force            0.000001     0.000010     YES
 Maximum Displacement     0.000003     0.000060     YES
 RMS     Displacement     0.000002     0.000040     YES

 Low frequencies ---   -0.0009   -0.0004    0.0010    3.2689    4.3149    5.0855
 Low frequencies ---  347.8792  561.2465  771.6103

Optimised molecule image

Jmol rotateable molecule

logfile: Media:HTHOMPSON_N2F2_OPTF_POP.LOG

Optimised NF molecule

Important geometric parameters

Optimised bond distance and angle for N₂F₂
r(N-F)=1.3Â
r(N=N)=1.23Â
θ(F-N=N)=120°

Vibrations

Mode	1	2	3	4	5	6
Wavenumber (cm-1)	348	561	772	949	987	1637
Symmetry	A1	A2	B2	A1	B2	A1
Intensity (arbitary units)	0.6	0	75	75	81	21

IR Spectra

Atomic charges

Charges of each atom

N	+0.22
F	-0.22

Molecular Orbital Diagram

Molecular Orbital	LCAO

Questions to answer

• The molecule from the log file does not have bonds between the F and N atoms, what is going on here?

There is a preset input length that Gaussview uses for each bond, the length of the bond between the F and N atoms is too long and exceeds the preset input length. There is still a bond there however Gaussview does not show it.

• How many vibrations are expected from the 3N-6 rule?

Vibrations = 3(4)-6 = 6 Vibrations expected

• Why are there only 4 peaks in the IR spectrum?

The Modes 1 and Modes 2 have an intensity of 0 and 0.6. The low intensity resulted in the peaks not showing on the IR spectrum, and the 4 modes with higher intensities show up on the spectra.

• Which vibration is the asymmetric N-F stretch?

Vibration 3 shows the asymmetric N-F stretch

• What is the nature of the highest energy vibration?

The highest energy vibration is the N=N symmetric stretch

• Which MOs are core orbital MOs?

MO 1-4 as they contain the different combinations of the 1s orbital phases of the 4 atoms