AM1 geometry optimization gave a bond length value of 1.43 angstroms
between each of the S=O bonds. A bond angle of 107.9 degrees was
present.
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PM3 geometry optimization gave a bond length value of 1.44 angstroms
between each of the S=O bonds. A bond angle of 106.1 degrees was
present.
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6-21G geometry optimization gave a bond length value of 1.53 angstroms
between each of the S=O bonds. A bond angle of 113.9 degrees was
present.
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6-31G geometry optimization gave a bond length value of 1.55 angstroms
between each of the S=O bonds. A bond angle of 113.2 degrees was
present.
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DZV geometry optimization gave a bond length value of 1.53 angstroms
between each of the S=O bonds. A bond angle of 112.8 degrees was
present.
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This is the electrostatic potential of SO2. The red areas represent the
lowest electrostatic potentials and the blue areas represent the highest
electrostatic potentials. Intermediate colors represent intermediate
potentials.
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The partial atomic charge on each atom is shown in the diagram on the
left. The values of the partial charges on each atom were created by the
symmetrical distribution of electrons in the chemical bonds.
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This is the highest occupied molecular orbital (HOMO) at orbital 16.
Orbital 16 was chosen for the HOMO because SO2 has a total number of 32
electrons, and the number of total electrons was divided by two.
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This is the lowest unoccupied molecular orbital (LUMO) at orbital 17.
Orbital 17 was chosen as the LUMO because the HOMO is in orbital 16.
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The vibrational modes for SO2 were extracted from a file
built with the DZV basis set due to the DZV producing the best optimized
geometry for the molecule.
The vibrational bend of SO2 that occurs at 464.22 cm¯¹ can be visualized in the diagram on the right. | ||||||||||||||
The symmetrical vibrational stretch of SO2 that occurs at 1504.29 cm¯¹ can be visualized in the diagram on the left.
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The asymmetrical vibrational stretch of the SO2 molecule that occurs at 1684.94 cm¯¹ can be visualized in the diagram on the right.
A reference IR Spectrum can be found on NIST. The reference spectrum contains three peaks that can be correlated to the above three vibrational modes, these peaks and a comparison are summarized below in Table 1. The two calculated peaks at 1504.29 cm¯¹ and 1684.94 cm¯¹ are both approximately 300 cm¯¹ above the reference peaks found on the NIST spectrum. This suggests that there are other factors affecting the vibrations that are unaccounted for in the DZV calculations. Table 1: Summary of calculated peaks and comparison to peaks from NIST
reference spectrum.
|
AM1 |
4.291332 D |
PM3 |
3.631559 D |
6-21G |
2.899024 D |
6-31G |
3.276975 D |
DZV |
3.437553 D |