Brickluci

Comments

It's great that you have a working wiki—you did a good job. However, your answers could have been elaborated more thoroughly. Also, it would have been nice if you had focused a bit more on enhancing the visual appeal of the wiki. 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	LKB_NH3_OPTF_POP.log
molecule	NH3
method	RB3LYP
basis set	6-31G(d,p)
final energy	-56.557769
RMS gradient	0.0000002
point group	C3V

Convergence

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:

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

Optimised Molecule

Static Image

Jmol Rotatable Molecule
Logfile: Media:LKB NH3 OPTF POP.LOG

Optimised NH₃ Molecule

Important geometric parameters

Optimised bond distance and angle for NH₃

coord	value
r(N-H)	1.02Â
θ(H-N-H)	106°

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	145	14	14	1	0	0

Computed IR Spectrum:

Charges

NBO charges image, colour coded red (negative) to green (positive):
The charge range is ±1.125e

Table of NH₃ charges:

Atom	Charge
N	-1.13
H	+0.38

Project Molecule:N₂F₂

Calculation Data

name of submitted log file	LKB_N2F2_OPTF_POP.log
molecule	N2F2
method	RB3LYP
basis set	6-31G(d,p)
final energy	-309.01241
RMS gradient	0.0000003
point group	C2V

Convergence

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

Low Frequencies

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

Optimised Molecule

Static Image

Jmol Rotatable Molecule
Logfile: Media:LKB N2F2 OPTF POP.LOG

Optimised N₂F₂ Molecule

Important geometric parameters

Optimised bond distances and angles for N₂F₂

coord	value
r(N-F)	1.39Â
r(F-F)	1.22Â
θ(F-N-N)	114°
θ(F-N-N-F)	0°

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	1	0	75	75	81	21

Computed IR Spectrum:

Questions:

• how many modes do you expect from the 3N-6 rule?

6, because there are 4 atoms, and 3(4)-6 = 6

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

Even though there are 6 modes, only 4 of them have a high enough intensity to appear in the spectrum.

• which vibration is the asymmetric N-F stretch?

Mode 3

• what is the nature of the highest energy vibration?

The highest energy vibration is mode 6, which is the N-N stretch

Charges

NBO charges image, colour coded red (negative) to green (positive):
The charge range is ±0.215e

Table of N₂F₂ charges:

Atom	Charge
N	-0.22
F	+0.22

Molecular Orbitals

• which MOs are core orbital MOs?

MOs 1-4 are the core orbitals, which don't take part in bonding.

Real MO	LCAO MO