Bosque's model was fit directly using experimental data of 426 compounds. The fitted m and C i values for C, Cl, H, N, O, and S are listed in Table . Accordingly, we have here used the QM7-X dataset 37 (see Sec. 6) to validate the accuracy and reassess the model parameters on a significantly larger swath of the CCS. In doing so, we have considered the first conformer for each entry in the QM7-X dataset; a total of ≈ 13 k structures. The linear regression parameters optimized on QM7-X yield the results listed in Table . Bosque's parameters hold up relatively well for QM7-X molecules, accounting for a correlation coefficient (R 2 value) of 0.65 with a mean absolute percentage error (MAPE) of 6.11 %. However, the re-fitted parameters improve the correlation coefficient to 0.72 and reduce MAPE value to 3.94 %, i.e., the prediction accuracy is increased by a factor of 1.6. Note that the presence of the intercept m in Eq. 4 is just an artifact of the model, since the prediction should be zero when no atoms are present. Inclusion or omission of m, however, changes neither the goodness of the regression, nor the numerical value of the atomic contributions to a meaningful degree (the mean absolute error of the linear model goes from 3.078 a.u. to 3.079 a.u.; similarly to what had also been observed by the authors). Therefore, we decided to include the intercept in our further analysis, to be consistent with Bosque's approach.