The variation of ΔΔG as a function of a toy model ligand composition
| No. of carbonyls | No. of water molecules | No. of carboxylates | ΔΔG |
| (kcal/mol) | |||
| 8 | 0 | 0 | 6.2 (3.9) |
| 7 | 1 | 0 | 4.9 (3.5) |
| 6 | 2 | 0 | 4.0 (3.1) |
| 5 | 3 | 0 | 3.2 (2.6) |
| 4 | 4 | 0 | 2.5 (2.3) |
| 6 | 0 | 0 | 3.6 (1.9) |
| 5 | 1 | 0 | 3.2 (1.7) |
| 4 | 2 | 0 | 2.5 (1.4) |
| 7 | 0 | 1 | 2.1 (−0.5) |
| 6 | 1 | 1 | 1.7 (−0.9) |
| 5 | 2 | 1 | 1.4 (−1.6) |
| 4 | 2 | 1 | 0.3 (−2.0) |
| 3 | 2 | 1 | −0.6 (−2.3) |
| No. of carbonyls | No. of water molecules | No. of carboxylates | ΔΔG |
| (kcal/mol) | |||
| 8 | 0 | 0 | 6.2 (3.9) |
| 7 | 1 | 0 | 4.9 (3.5) |
| 6 | 2 | 0 | 4.0 (3.1) |
| 5 | 3 | 0 | 3.2 (2.6) |
| 4 | 4 | 0 | 2.5 (2.3) |
| 6 | 0 | 0 | 3.6 (1.9) |
| 5 | 1 | 0 | 3.2 (1.7) |
| 4 | 2 | 0 | 2.5 (1.4) |
| 7 | 0 | 1 | 2.1 (−0.5) |
| 6 | 1 | 1 | 1.7 (−0.9) |
| 5 | 2 | 1 | 1.4 (−1.6) |
| 4 | 2 | 1 | 0.3 (−2.0) |
| 3 | 2 | 1 | −0.6 (−2.3) |
The numbers between parentheses are for the AMBER force field. The difference in hydration free energy between Na+ and K+ is 18.4 kcal/mol for the CHARMM force field and 17.7 kcal/mol for the AMBER force field. The CHARMM force field cation Lennard-Jones parameters Emin and Rmin/2 were −0.0469, 1.40375, and −0.087, 1.76375, for sodium and potassium, respectively; pair-specific Lennard-Jones parameters for the ion–carbonyl interactions used for potassium and sodium were −0.1021763, 3.64275, and −0.07502, 3.2975, respectively (units are kcal/mol for Emin and Å for Rmin).