A Coulomb Hamiltonian is a many-particle Schroedinger operator with pair interactions proportional to reciprocal distance. For 
electrons with two spin states and fixed
distinct nuclei at 
with charges 
, its atomic-unit form is
 |
It acts on the antisymmetric space 
. A fixed nuclear
repulsion term may be added without affecting successive-electron energy differences.
Write 
and 
. Strict binding of the 
th electron means 
.
