ELF Labeler - Theory¶
Our classification of ELF basins into various Lewis-like chemical features is based on three metrics.
- Topology While most maxima in the ELF are points, under the right symmetry they may be ring-like or cage-like.
- Position The location of an ELF basin's maximum is influenced by the atoms around them.
- Polarization Index The degree of polarization can be estimated from the ratio of contributions from each overlaping QTAIM atom with each ELF basin. A value of 0 is fully non-polar while a value of 1 is fully polar.
The following table summarized the current labeling scheme.
| Topology | Position | Polarization Index | Result |
|---|---|---|---|
| Point/Ring | Along Bond | 0-0.5 | Covalent bond |
| Point/Ring | Along Bond | 0.5-1.0 | Ionic bond |
| Point/Ring | Not Along Bond | <1.0 | Multi-centered bond |
| Cage | — | <1.0 | Ionic shell |
| Cage | — | 1.0 | Atomic shell |
| Point | Atom center | 1.0 | Atomic shell |
| Point | Elsewhere | 1.0 | Lone pair |
In reality, many extremely polar features (e.g. lone-pairs, core shells) may have some overlap with multiple atoms. This decreases the polarization index very slightly, so for features requiring full polarization we apply a small tolerance.
Note
The 'ElfLabeler' is a work in progress and we are looking to improve it. If you have suggestions or desired features, please let our team know on our github issues page.