Beyond the Harmonic Oscillator; Highlights of Selected Studies of Vibrational Potential Energy Functions
Abstract
:1. Introduction
2. Experimental and Theoretical Results
2.1. Harmonic Oscillator
2.2. Ammonia Inversion
2.3. Carbonyl Inversion in the Excited State
2.4. Ring Puckering
2.5. Anomeric Effect
2.6. Pseudorotation
2.7. Triplet-State Ring Puckering
2.8. Cyclohexane
2.9. Internal Rotation
2.10. π-Type Hydrogen Bonding
2.11. Pyridine and Sir Harry Kroto
3. Conclusions
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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C=O Inversion Barrier (cm−1) | |
---|---|
0 | |
672 | |
939 | |
2149 |
Frequency (cm−1) | Relative Intensity | ||||
---|---|---|---|---|---|
Transition | Observed | Calculated | ∆ | Observed | Calculated |
vT = 0 | |||||
1–2 | 88.8 | 88.6 | 0.2 | 0.80 | 0.90 |
2–3 | 83.5 | 83.5 | 0.0 | 0.76 | 0.87 |
3–4 | 103.8 | 103.6 | 0.2 | (1.00) | (1.00) |
4–5 | 114.9 | 114.8 | 0.1 | 0.77 | 0.83 |
5–6 | 124.9 | 124.8 | 0.1 | 0.75 | 0.61 |
6–7 | 133.3 | 133.4 | −0.1 | 0.50 | 0.41 |
7–8 | 141.1 | 140.9 | 0.2 | 0.40 | 0.26 |
8–9 | 147.4 | 147.7 | −0.3 | 0.22 | 0.15 |
9–10 | 152.7 | 153.9 | −1.2 | 0.17 | 0.09 |
10–11 | 160.4 | 159.9 | 0.5 | 0.06 | 0.05 |
0–3 | 191.2 | 191.1 | 0.1 | 0.15 | 0.27 |
1–4 | 275.9 | 275.6 | 0.3 | 0.20 | 0.11 |
2–5 | 301.8 | 301.8 | 0.0 | 0.06 | 0.08 |
3–6 | 343.2 | 343.2 | 0.0 | 0.06 | 0.05 |
4–7 | 372.2 | 372.9 | −0.7 | 0.05 | 0.03 |
5–8 | 398.9 | 398.1 | 0.8 | 0.04 | 0.02 |
6–9 | 422.1 | 422.0 | 0.1 | 0.02 | 0.01 |
Experimental Fit | Theoretical | ||||||||
---|---|---|---|---|---|---|---|---|---|
a | CCSD/cc-pVTZ | MP2/cc-pVTZ | |||||||
Molecule | Barrier | Barrier | Barrier | ||||||
cm−1 | Å | Degrees | cm−1 | Å | Degrees | cm−1 | Å | Degrees | |
| 510 | ±0.142 | ±29.6° | 586 | ±0.142 | ±29.5° | 821 | ±0.153 | 31.9° |
| 15 | ±0.062 | ±13.4° | 0 | ±0.001 | ±0.2° | 21 | ±0.069 | 14.8° |
| 273 | ±0.141 | ±26.9 | 243 | ±0.133 | ±25.5° | 412 | ±0.152 | 29.0° |
| 378 | ±0.162 | ±30.4° | 339 | ±0.148 | ±27.8° | 512 | ±0.164 | 30.9° |
| 440 | ±0.163 | ±31.9° | 472 | ±0.163 | ±31.7° | 654 | ±0.176 | 34.5° |
| 87 | ±0.130 | ±22.3° | 89 | ±0.130 | ±22.4° | 160 | ±0.150 | 25.8° |
| --- | --- | --- | 409 | ±0.156 | ±30.1° | 567 | ±0.169 | 32.6° |
| --- | --- | --- | 1 | ±0.047 | ±7.8° | 24 | ±0.104 | 17.1° |
| 2 | ±0.043 | ±4.6° | 36 | ±0.073 | ±15.5° | 114 | ±0.097 | 20.8° |
Molecule | Linkage | Value | a (kcal/mole) |
---|---|---|---|
| OCO | 1.00 | 5.97 b |
| OCS | 0.82 | 4.90 |
| OCSe | 0.66 | 3.94 |
| SCS | 0.60 | 3.58 |
| SCSe | 0.45 | 2.69 |
| SeCSe | 0.32 | 1.91 |
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Ocola, E.J.; Laane, J. Beyond the Harmonic Oscillator; Highlights of Selected Studies of Vibrational Potential Energy Functions. Molecules 2025, 30, 1492. https://doi.org/10.3390/molecules30071492
Ocola EJ, Laane J. Beyond the Harmonic Oscillator; Highlights of Selected Studies of Vibrational Potential Energy Functions. Molecules. 2025; 30(7):1492. https://doi.org/10.3390/molecules30071492
Chicago/Turabian StyleOcola, Esther J., and Jaan Laane. 2025. "Beyond the Harmonic Oscillator; Highlights of Selected Studies of Vibrational Potential Energy Functions" Molecules 30, no. 7: 1492. https://doi.org/10.3390/molecules30071492
APA StyleOcola, E. J., & Laane, J. (2025). Beyond the Harmonic Oscillator; Highlights of Selected Studies of Vibrational Potential Energy Functions. Molecules, 30(7), 1492. https://doi.org/10.3390/molecules30071492