Table 1.
Experimental and computed hydration free energies (kcal/mol) of compounds in SAMPL4 hydration challenge set, for different partial charge sets coupled with GAFF.
| ID | Exp. | RESP | IPolQ- Mod |
AM1-BCC | Vcharge | AM1-BCC* | |
|---|---|---|---|---|---|---|---|
| 01 | −23.6 ± 0.3 | −27.1 | −25.4 | −19.4 | −15.6 | −18.6 | (−22.3) |
| 02 | −2.5 ± 0.9 | −2.3 | −2.1 | −2.3 | −1.8 | −2.6 | |
| 03 | −4.8 ± 0.3 | −4.1 | −4 | −2.5 | −1.6 | −2.6 | (−4.2) |
| 04 | −4.5 ± 0.2 | −3.5 | −3.3 | −2.6 | −1.6 | −2.5 | (−4.2) |
| 05 | −5.3 ± 0.1 | −3.2 | −3 | −3.4 | −3.6 | −3.5 | |
| 06 | −5.3 ± 0.2 | −7.1 | −7.2 | −4 | −2.9 | −4.1 | (−5.2) |
| 09 | −8.2 ± 0.8 | −10.1 | −8.6 | −9.8 | −11.3 | −9.9 | (−11.4) |
| 10 | −6.2 ± 0.4 | −6 | −4.9 | −5.9 | −5.0 | −6.1 | (−7.6) |
| 11 | −7.8 ± 0.8 | −8.6 | −7.5 | −9 | −9.4 | −9.2 | (−10.6) |
| 12 | −3.8 ± 0.2 | −3.7 | −3.7 | −3 | −4.7 | −3.3 | |
| 13 | −4.4 ± 0.4 | −5 | −4.5 | −3.3 | −2.1 | −3.4 | (−5.1) |
| 14 | −4.1 ± 0.2 | −3.5 | −3.3 | −3.2 | −4.9 | −3.6 | |
| 15 | −4.5 ± 0.1 | −3.7 | −3.6 | −3.5 | −4.3 | −3.8 | |
| 16 | −3.2 ± 0.3 | −5.6 | −5.3 | −3.2 | −2.3 | −3.4 | (−5.3) |
| 17 | −2.5 ± 0.3 | −2.9 | −2.8 | −3 | −4.7 | −3.4 | |
| 19 | −3.8 ± 0.1 | −3.1 | −2.8 | −4 | −1.6 | −4.4 | |
| 20 | −2.8 ± 0.1 | −2.6 | −2 | −3.5 | −0.7 | −3.9 | |
| 21 | −7.6 ± 0.1 | −8 | −9 | −7.7 | −4.5 | −7.9 | |
| 22 | −6.8 ± 0.1 | −7.2 | −6.4 | −7.3 | −4.4 | −7.7 | |
| 23 | −9.3 ± 0.6 | −4.1 | −3.9 | −7.8 | −3.3 | −8.2 | |
| 24 | −7.4 ± 0.6 | −4 | −3.7 | −7.7 | −3.0 | −8.3 | |
| 25 | −5.7 ± 0.2 | −4.5 | −4.1 | −3.8 | −3.4 | −3.8 | (−5.2) |
| 26 | −5.3 ± 0.1 | −5.4 | −5.1 | −5.9 | −5.2 | −6.0 | |
| 27 | −4.8 ± 0.4 | −10.7 | −9.7 | −5 | −12.4 | −5.5 | |
| 28 | −4.3 ± 0.4 | −9.6 | −8.7 | −4.9 | −12.1 | −5.4 | |
| 29 | −1.7 ± 0.1 | −4 | −3.7 | −1.3 | −5.7 | −1.6 | |
| 30 | −2.3 ± 0.1 | −3.7 | −3.5 | −2.9 | −2.6 | −3.2 | |
| 32 | −7.3 ± 0.1 | −6.6 | −6.1 | −5.3 | −4.2 | −5.3 | (−6.9) |
| 33 | −7.0 ± 0.1 | −7.2 | −6.7 | −7.1 | −6.2 | −7.1 | (−8.9) |
| 34 | −5.8 ± 0.1 | −7.3 | −7.3 | −4.4 | −3.2 | −4.5 | (−5.6) |
| 35 | −4.7 ± 0.1 | −5 | −4 | −4.7 | −5.1 | −4.9 | (−5.0) |
| 36 | −5.7 ± 0.1 | −5.3 | −4.6 | −4.8 | −2.7 | −4.7 | (−6.3) |
| 37 | −5.9 ± 0.1 | −7.5 | −7.5 | −4.7 | −3.4 | −4.6 | (−5.8) |
| 38 | −3.9 ± 0.1 | −4.2 | −3.6 | −4.4 | −5.1 | −4.6 | |
| 39 | −0.9 ± 0.1 | −0.3 | −0.2 | −0.6 | 0.6 | −0.8 | |
| 41 | −5.1 ± 0.1 | −2.5 | −3.3 | −3.8 | −1.9 | −3.9 | |
| 42 | −3.1 ± 0.1 | −1.5 | −1.6 | −1.7 | −1.7 | −1.7 | |
| 43 | 0.1 ± 0.1 | 1.4 | 1.3 | 1.4 | 1.4 | 1.1 | |
| 44 | −5.1 ± 0.1 | −4.3 | −3.9 | −4 | −3.5 | −4.2 | |
| 45 | −11.5 ± 0.3 | −11.5 | −10.2 | −13.3 | −10.9 | −13.7 | |
| 46 | −9.4 ± 0.7 | −9.2 | −9.3 | −11 | −8.6 | −11.6 | |
| 47 | −14.2 ± 1.1 | −13.1 | −11.9 | −12.9 | −11.5 | −13.3 | (−14.7) |
| 48 | −11.9 ± 0.4 | −11.3 | −10.3 | −13.6 | −9.9 | −14.2 | |
| 49 | −3.2 ± 0.1 | −3 | −2.5 | −3.4 | −2.4 | −4.0 | |
| 50 | −4.1 ± 0.1 | −3 | −2.4 | −4.8 | −1.9 | −5.3 | |
| 51 | −9.5 ± 0.3 | −11.3 | −9.5 | −10.5 | −8.8 | −11.2 | (−11.3) |
| 52 | −2.9 ± 0.7 | −2.2 | −1.5 | −2.5 | −0.9 | −2.8 | |
| MAE | −0.1 | 0.4 | 0.4 | 1.0 | 0.1 | ||
| MUE | 1.3 | 1.4 | 1.0 | 2.3 | 1.1 | ||
| RMSE | 1.9 | 1.8 | 1.3 | 3.0 | 1.4 | ||
| R2 | 0.82 | 0.82 | 0.90 | 0.53 | 0.87 | ||
| Kendall's τ | 0.64 | 0.64 | 0.77 | 0.47 | 0.73 | ||
*
Two sets of predictions from another SAMPL4 participant: one using the standard GAFF with AM1-BCC charges, and the other (shown in parenthesis) with modified GAFF AM1-BCC parameters for the hydroxyl group [41]. The statistical uncertainty of the computed hydration free energies is less than 0.1 kcal/mol, in all cases.