01336632

BH₃

Item Table


   Item               Value     Threshold  Converged?
 Maximum Force            0.000002     0.000450     YES
 RMS     Force            0.000001     0.000300     YES
 Maximum Displacement     0.000008     0.001800     YES
 RMS     Displacement     0.000004     0.001200     YES

Frequency analysis log file

Media:DEXOSEMAN_BH3_FREQ.LOG

Low Frequencies


 Low frequencies ---   -0.7334   -0.4455   -0.0055   11.1069   15.1087   15.1264
 Low frequencies --- 1163.0254 1213.2022 1213.2049

test molecule

Vibrational Spectrum for BH₃


wavenumber (cm^-1	Intensity (arbitrary units)	symmetry	IR active?	type
1163	93	A₁	yes	out-of-plane bend
1213	14	E	very slight	bend
1213	14	E	very slight	bend
2582	0	A₁	no	symmetric stretch
2715	126	E	yes	asymmetric stretch
2715	126	E	yes	asymmetric stretch

Good consideration of the accuracy of the reported values in the table but the symmetries are wrong (they match the NH3 example but not the ones in your BH3 file!) Smf115 (talk) 22:14, 13 May 2019 (BST)

There are three peaks present, where as we would expect 6. This is because of degeneracy seen at 1163 cm^-1 and at 2715 cm^-1. Furthermore, the absorption at 2582 cm^-1 is 0. This leaves us with three peaks which is consistent with the spectrum.

Molecular Orbitals

^-1

Shown above is the molecular orbital diagram of BH₃ aligned with the computational MO representations. The unasigned MO on the bottom left of the diagram is the MO of the low lying, deep 1s boron electrons. They're not mixing and as such are not included on the diagram. The above MO diagram was taken from Lecture 4 tutorial.

1. Comparing the real and LCAO MOs allows us to see that there are not any significant differences. 
2. This tells us that qualitative MO theory is a very good approximation of the real thing. The MOs made by the computer 
programme align with the theory suggesting that MO theory is indeed accurate and trustworthy.

Correct inclusion of the MOs on to the diagram, to improve you could have considered the subtle differences between some of the real and LCAO MOs. Smf115 (talk) 22:16, 13 May 2019 (BST)

Project Section

Overall, a very incomplete report, which is a shame because the part you’ve completed is a good attempt. Smf115 (talk) 22:17, 13 May 2019 (BST)

References

1. Taken from lecture 4 Tutorial

BH3