Table 3. Properties of the Original and Extended IPolQ Charge Setsa.
| accuracyb |
||||
|---|---|---|---|---|
| dipeptide | original QIPol,c | Qvac,d | Qvac + ΔQc | max ΔQ, atome |
| Ala | 1.57 | 1.81 | 1.74 | 0.06, CB |
| Arg | 1.90 | 2.42 | 1.95 | 0.05, CA |
| Asn | 1.65 | 2.01 | 1.72 | 0.10, CA |
| Asp | 1.91 | 2.58 | 1.97 | 0.08, CB |
| Cys | 2.39 | 2.76 | 2.46 | 0.07, CA |
| Gln | 1.63 | 1.99 | 1.75 | 0.09, OE1 |
| Glu | 1.79 | 2.44 | 1.87 | 0.08, CA |
| Gly | 1.57 | 1.93 | 1.73 | 0.01, CA |
| Hie | 1.85 | 2.20 | 1.95 | 0.12, ND1 |
| Ile | 1.75 | 2.05 | 1.77 | 0.11, CG2 |
| Leu | 1.77 | 2.00 | 1.81 | 0.15, CG |
| Lys | 1.92 | 2.43 | 1.94 | 0.05, CE |
| Met | 2.12 | 2.35 | 2.20 | 0.12, CE |
| Phe | 1.61 | 1.96 | 1.67 | 0.08, CA |
| Pro | 1.75 | 1.79 | 1.86 | 0.13, C |
| Ser | 1.77 | 2.16 | 1.84 | 0.09, OG |
| Thr | 1.77 | 2.11 | 1.81 | 0.12, OG1 |
| Trp | 1.69 | 2.06 | 1.77 | 0.06, CA |
| Tyr | 1.64 | 1.97 | 1.76 | 0.08, OH |
| Val | 1.56 | 1.85 | 1.65 | 0.17, CB |
a
Errors and charge variations are expressed for a restraint of VGP = 0.005 kcal/(mol·e2-instance) applied to all perturbation charges.
b
Root-mean-squared error (rmse) of fitted MM charges in replicating the QM target electrostatic potential.
c
The target is the average electrostatic potential of the solute’s MP2/cc-pvTZ wave function in vacuum and in the solvent reaction field potential due to TIP4P-Ew water.
d
The target is the electrostatic potential of the solute’s MP2/cc-pvTZ wave function in vacuum.
e
Maximum absolute deviation in partial charges unique to this residue; backbone atoms frequently showed ΔQ of 0.06–0.10, as shown in the Supporting Information.