TABLE II.
The fundamental intermolecular vibrational energy levels in cm−1 of the CO2 barrel-shaped trimer obtained with the harmonic approximation, as well as VSCF, VMP2, and VCI methods.
| HAR | HAR | VSCF | VMP2 | VCI | |
|---|---|---|---|---|---|
| CCSD(T)-F12b/aVDZ | mbCO2 | mbCO2 | mbCO2 | mbCO2 | |
| ν1(A) | 9.69 | 9.3 | 11.6 | 9.7 | 10.5 |
| ν2(A) | 30.38 | 26.7 | 25.6 | 21.4 | 25.7 |
| ν3(A) | 37.68 | 33.2 | 30.6 | 29.0 | 29.3 |
| ν4(B) | 42.85 | 39.9 | 33.7 | 30.9 | 32.2 |
| ν5(A) | 59.51 | 53.6 | 46.6 | 39.4 | 45.5 |
| ν6(B) | 57.62 | 52.5 | 47.6 | 44.6 | 49.2 |
| ν7(A) | 89.38 | 85.0 | 77.1 | 69.5 | 74.9 |
| ν8(B) | 100.22 | 99.5 | 89.9 | 88.1 | 88.8 |
| ν9(A) | 117.22 | 111.7 | 96.8 | 86.6 | 91.6 |