Currently bonds cannot be created automatically from inside a file,
using either the geometric
Length or the topological
Delaunay
methods. Each bond object contains thus a complete description of one bond only.
To specify the atoms forming the bond, the bond parameters
parent1,
parent2 must point to the atom
id attributes, which are
different for each atom.
Example: <bond ... parent1="C1" parent2="C2"/> (no default)
Allowed values: alphanumeric expression representing a unique atom id
with less than 20 characters (defined in GAMGI_ENGINE_TOKEN) (required)