Table 3. Measured and Calculated VRT Levels and Tunneling Splittings for the (H2O)2 Dimera.
| experiment | HBB2 | CCpol-8s/f | MB-pol | ||
|---|---|---|---|---|---|
| Ka = 0 | |||||
| OO | (2) | 153.62(1.88) | 148.57(1.14) | 149.63(1.23) | 154.31(2.41) |
| (1) | 145.00(3.48) | 143.20(3.27) | 149.44(1.97) | ||
| AT | (1) | 128.91(0.74) | 132.10(1.48) | 129.44(0.24) | |
| (2) | 120.19(0.74) | 121.01(8.41) | 117.50(8.67) | 119.07(10.15) | |
| AW | (2) | 108.89(0.02) | 105.78(0.03) | 107.82(0.10) | 108.87(0.13) |
| (1) | 107.93(2.95) | 105.35(1.99) | 109.23(3.29) | 108.38(3.24) | |
| DT | (1) | 116.54(4.84) | 113.35(5.91) | 113.83(5.61) | |
| (2) | 64.52(2.54) | 67.18(2.03) | 61.33(2.48) | 61.31(2.54) | |
| GS | (2) | 11.18(0.65) | 10.16(0.60) | 12.75(0.61) | 12.05(0.69) |
| (1) | 0.00(0.75) | 0.00(0.68) | 0.00(0.72) | 0.00(0.81) | |
| Ka = 1 | |||||
| OO | (2) | 152.50(1.12) | 152.07(1.48) | 156.60(2.71) | |
| (1) | 150.52(1.04) | 153.54(2.54) | 152.69(4.13) | ||
| AT | (1) | 142.25(4.33) | 142.42(4.04) | 143.68(4.87) | |
| (2) | 136.24(5.31) | 136.52(4.66) | 137.04(5.95) | ||
| AW | (2) | 123.56(3.41) | 122.25(2.48) | 123.12(3.16) | 123.65(3.83) |
| (1) | 109.98(5.24) | 108.95(4.55) | 108.28(4.76) | 109.65(5.89) | |
| DT | (1) | 94.25(2.66) | 92.18(3.34) | 91.22(3.47) | |
| (2) | 87.75(1.11) | 89.55(0.54) | 86.37(1.32) | 85.63(1.00) | |
| GS | (2) | 14.39(0.70) | 14.00(0.64) | 15.45(0.67) | 15.04(0.77) |
| (1) | 11.66(0.54) | 11.50(0.49) | 12.36(0.51) | 12.18(0.48) | |
a
The energy levels are labeled as ground state (GS), donor torsion (DT), acceptor wag (AW), acceptor twist (AT), and intermolecular stretch (OO). The energies (in cm–1) correspond to the origins o1(K) and o2(K) of the levels (1) and (2) with quantum numbers K = 0 and K = 1, respectively. The values in parentheses are the interchange tunneling splittings i1(K) and i2(K). The values for HBB2, which corresponds to the 2B term of WHBB are taken from ref (295), those for CCpol-8sf from ref (296), and those for MB-pol from ref (191). The experimental values are taken from refs (297−301).