Table 6.
The A-A’ atomic energy (kJ/mol) terms of water in various environments. Grid is (15,15). The average value is given in the last row with the SD in brackets. Method: 2PDM-M/CCSD(T)/uncontracted 6–31 + G(d, p). Figure 1 displays the first and second solvating waters of protonated methylamine and the formate ion
| Molecule | O | H1 | H2 | sum | O | H1 | H2 | sum |
|---|---|---|---|---|---|---|---|---|
| H2 O (reference molecule) | 128.3 | 19.8 | 19.8 | 167.9 | 0.0 | 0.0 | 0.0 | 0.0 |
| H2O.HOH (acceptor) | 130.7 | 19.9 | 19.9 | 170.5 | 2.4 | 0.1 | 0.1 | 2.6 |
| H2O.HOH (donor) | 132.3 | 20.5 | 17.5 | 170.3 | 4.1 | 0.7 | −2.3 | 7.1 |
|
H2O.H2O.H2Oa Middle H2O |
132.9 | 20.0 | 20.0 | 172.9 | 4.6 | 0.2 | 0.2 | 5.0 |
|
H2O.H2O.H2Oa Terminal H2O (x2) |
132.3 | 20.5 | 17.8 | 170.6 | 4.0 | 0.7 | −2.0 | 6.8 |
| NH3.H2O | 134.1 | 21.0 | 17.3 | 172.4 | 5.8 | 1.2 | −2.5 | 9.5 |
| NH4+.H2O | 130.3 | 19.0 | 19.0 | 168.4 | 2.1 | −0.8 | −0.8 | 3.7 |
| CH3NH3+.H2O | 130.6 | 19.4 | 19.4 | 169.3 | 2.3 | −0.4 | −0.4 | 3.2 |
| CH3NH3+.(H2O)2 Fig. 1 (1) | 130.4 | 19.5 | 19.5 | 169.5 | 2.2 | −0.9 | −0.9 | 3.9 |
| CH3NH3+.(H2O)2 Fig. 1 (2) | 130.4 | 19.5 | 19.5 | 169.5 | 2.2 | −2.4 | −0.3 | 4.9 |
| HCO2−.H2O | 145.1 | 19.0 | 19.5 | 183.5 | 16.8 | 0.1 | −0.3 | 17.2 |
| HCO2−.(H2O)2 Fig. 1 (1) | 145.4 | 17.4 | 21.5 | 184.4 | 17.2 | 0.3 | 1.7 | 19.2 |
| HCO2−.(H2O)2 Fig. 1 (2) | 143.0 | 19.9 | 17.7 | 180.7 | 14.8 | −2.1 | −2.1 | 19.0 |
| CH4.H2O | 128.7 | 20.1 | 20.1 | 168.9 | 0.4 | −1.0 | 0.3 | 1.7 |
| H5O2+ | 136.4 | 17.7 | 17.6 | 171.7 | 8.1 | −0.8 | −2.2 | 11.0 |
| H7O3+ | 132.6 | 18.8 | 18.7 | 170.0 | 4.3 | −19.8 | −1.1 | 25.2 |
| H9O4+ | 132.1 | 19.1 | 19.2 | 170.3 | 3.8 | −19.8 | −0.7 | 24.3 |
|
Average (SD) include H2O |
133.9 (5.3) | 19.5 (0.9) | 19.1 (1.1) | 172.4 (5.1) | 5.6 (5.3) | −0.3 (0.9) | −0.8 (1.1) | 7.3 (6.1) |
a The water trimer was forced to be a linear geometry (i.e open structure) rather than a cyclic one, as is found in the minimum energy form