... electrons1
According to the antisymmetry principle for fermions, of which the Pauli principle  is a direct result.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
... way.2
Some texts talk about the ``average'' electron repulsion term in the Fock operator; I find this misleading in that Hartree-Fock uses the same instantaneous interelectron repulsion term as CI--it's the same Hamiltonian! The restriction to a single Slater determinant is what causes the averaging of interelectron repulsions.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
... expect!3
However, state-of-the-art determinant-based CI algorithms often include computational simplifications if the Ms = 0 component is used [16].
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
...).4
Reference [28] contains a minor mistake, giving (pq|rs) as $\langle pq \vert rs \rangle$.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
... spin-orbitals.5
In the determinant CI expansion, we restrict all determinants to a single value of Ms.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
...+1.6
This differs somewhat from Duch [27], who sometimes uses ${\bar Y}(e, o)$ to denote the arc entering vertex (e, o) in reverse-lexical addressing.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
C. David Sherrill
2000-04-18