Digglefr

lab marking

You have a good working wiki. You reported incorrect charge on H-atom of NH3 and did not report all the geometric parameters of N2F2. Overall, a good attempt. If you have any specific questions, do email Prof. Hunt

NH₃ molecule

Calculation Data

Name of submitted log file	DIGGLE_NH3_OPTIMISATION.LOG
Molecule	NH3
Point Group	C3V
Method	RB3LYP
Basis Set	6-31G(d,p)
Final energy	-56.557769 Hartree
RMS Gradient	1.53e-07 Hartree/Bohr

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

Optimized Molecule Image

Optimized Molecule Calculation

Media:DIGGLE_NH3_OPTIMISATION.LOG

Jmol Rotatable Molecule

Optimized NH3 Molecule

Important Geometric Parameters

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

Low Frequencies

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

Frequency Analysis

name of submitted log file: DIGGLE_NH3_OPTIMISATION.LOG

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 Spectrum

Charge Data

name of submitted log file	DIGGLE_NH3_OPTIMISATION.LOG
Atom	Charge
N	-1.13
H	0.34

Project molecule

Calculation Data

Name of submitted log file	DIGGLE_N2F2_OPTIMISATION.LOG
Molecule	N2F2
Point Group	C2V
Method	RB3LYP
Basis Set	6-31G(d,p)
Final energy	-309.01241 Hartree
RMS Gradient	3.17e-07 Hartree/Bohr

Item Table

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

Optimized Molecule Image

The image does not show bonds between F and N. This is not because they are not there, but because gaussian only shows bonds if they are under a certain length parameter, and the N-F bond exceeds this parameter so they don't show up.

Optimized Molecule Calculation

Media:DIGGLE_N2F2_OPTIMISATION.LOG

Jmol Rotatable Molecule

Optimized NF2 Molecule

Important Geometric Parameters

Optimized bond length and angle for N₂F₂
r(N-F)=1.39Â
θ(F-N-N)=114°

Low Frequencies

Low frequencies ---   -0.0015   -0.0012   -0.0010    3.2225    4.3532    5.1001
Low frequencies ---  347.8772  561.2472  771.6105

Frequency Analysis

name of submitted log file: DIGGLE_N2F2_OPTIMISATION.LOG

Mode	1	2	3	4	5	6
Wavenumber (cm-1)	348	561	772	949	987	1634
Symmetry	A1	A2	B2	A1	B2	A1
Intensity (arbitrary units)	1	0	75	75	81	21

IR Spectrum

IR Spectrum Analysis

expected amount of vibrational modes from the 3n-6 rule would be 3. The three vibrational modes observed in this molecule are those with symmetry of A1, A2, and B2 as N2F2 is in C2V point group.

There are two vibrations that correlate to the N-F asymmetric stretch. The first is mode 3, where the stretch is created by both the Fluorine and Nitrogen moving. The second is mode 5, where it is only the Nitrogen moving.

The highest energy vibration is the N=N stretch. This makes sense because vibrating a double bond takes more energy than vibration a single bond, and this is the only vibration along a double bond.

The only vibrations that are visible in IR are those that cause a change in dipole. Out of the 6 calculated vibrations, only 4 show in the IR spectrum because only four cause a change in dipole. The four that show are the asymmetric N-F stretch (Fluorine and Nitrogen moving), the symmetric N-F stretch (Fluorine and Nitrogen moving), the asymmetric N-F stretch (only Nitrogen moving), and N=N stretch (both Nitrogen moving). There is one other vibration that should show in the IR as it does cause a change in dipole, the Fluorine scissoring, but this has a very low calculated intensity in IR (1) so the peak is probably too small to be visible, especially since the other peaks have intensities between 21-81.

Charge Data

name of submitted log file	DIGGLE_N2F2_OPTIMISATION.LOG
Atom	Charge
N	0.22
F	-0.22

MO Analysis - Core Orbitals

The Core orbitals in MO theory are those that very close to their nuclei. The bonding and anti-bonding interactions cancel each other out, making them non bonding orbitals. These orbitals come from the inner shells of each nuclei. In N2F2, the core orbitals are molecular orbitals no. 1-4.

MO Analysis - Calculated Molecular Orbital 9

MO Analysis - LCAO drawing of Molecular Orbital 9