Table 4. The MS-QM/MM-LR Correlations (eq 5) for Different Tautomer and Species Composition: Optimized Coefficients and Statistical Indices.

							LOOc		MC-LGOd
tautomer	species	α × 10–3(mol/kcal)a	γ × 10–3(1/Å2)b	κ	r2	RMSE	q2	RMSE	q2	RMSE
single	single	–1.212 ± 1.289	–8.985 ± 8.451	1.151 ± 0.896	0.662	0.431	0.617	0.458	0.616	0.459
single	multi	–1.291 ± 1.026	–8.664 ± 7.211	1.000 ± 0.758	0.734	0.382	0.690	0.412	0.691	0.411
multi	single	–1.338 ± 0.801	–8.334 ± 5.002	0.960 ± 0.507	0.839	0.297	0.819	0.315	0.819	0.315
multi	multi	–1.326 ± 0.591	–7.761 ± 2.261	1.160 ± 0.358	0.906	0.228	0.897	0.237	0.894	0.241

^aScales the QM/MM energy term.

^bScales the SASA term.

^cLeave-one-out cross-validation: the results reported as RMSE and the squared predictive correlation coefficient (q²).

^dMonte Carlo leave-group-out cross-validation: the compounds were randomly divided into 7 groups, and each group of ∼9 compounds was used once as a test set; the procedure was repeated 10 times.