Covalent Bond Radii

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).

UCSF Computer Graphics Laboratory / June 2006