A self-paired orbital is an orbital that equals its paired orbital,
Equivalently, if and only if . For a nondiagonal self-paired orbital, the opposite arcs of the corresponding orbital digraph can therefore be identified to give the edges of an undirected graph, namely an orbital graph.
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Weisstein, Eric W. "Self-Paired Orbital." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/Self-PairedOrbital.html
that equals its paired orbital,
if and only if 
.
For a nondiagonal self-paired orbital, the opposite arcs
of the corresponding orbital digraph can therefore
be identified to give the edges of an undirected
graph, namely an orbital graph.
