Table 6. Descriptor Importance of VSURF Regression Model, Ordered by Decreasing Importancea.
| VSURF | Spearman ρ | |
|---|---|---|
| Oxygen balance | 0.111 | –0.668 |
| Moment1 | 0.100 | 0.664 |
| Functional group | 0.095 | 0.659 |
| Q (kcal/g) | 0.081 | –0.668 |
| ZPE (kJ/g) | 0.054 | 0.280 |
| H acceptor | 0.054 | 0.589 |
| Moment3 | 0.054 | 0.193 |
| Max charge | 0.040 | 0.493 |
| Moment2 | 0.039 | –0.543 |
| Gas C | 0.039 | 0.085 |
| Band Energy | 0.033 | –0.582 |
| Lab | 0.033 | 0.560 |
| HOMO–LUMO gap | 0.031 | 0.577 |
| N[CO] | 0.024 | 0.178 |
| Min charge | 0.024 | 0.326 |
| N[CHH] | 0.021 | 0.141 |
| N[N] | 0.020 | 0.196 |
| Method | 0.005 | –0.432 |
| Grit | 0.005 | 0.415 |
a
Importance corresponds to the
expected decrease in 
when each descriptor is randomly permuted.
The last column gives the Spearman correlation between the descriptor
and drop energy (in log J).