Chimera uses approximate covalent bond radii to determine connectivity (when not specified in the input structure file) and to generate crude bond lengths for structure building.
| Selected covalent bond radii (Å) | |
|---|---|
| H | 0.23 |
| B | 0.83 |
| C | 0.68 |
| N | 0.68 |
| O | 0.68 |
| F | 0.64 |
| Si | 1.20 |
| P | 1.05 |
| S | 1.02 |
| Cl | 0.99 |
| Se | 1.22 |
| Br | 1.21 |
| I | 1.40 |
A complete list, obtained many years ago from documentation from the Cambridge Crystallographic Data Centre, can be found in Table III of:
E.C. Meng and R.A. Lewis, "Determination of Molecular Topology and Atomic Hybridization States from Heavy Atom Coordinates" J Comput Chem 12:891 (1991).