ese result in superior scaling for smaller
molecules and an up to 7 fold increase in performance in very large
sparse systems.</I>

<H2>Background</H2>

 <P>The simplest N-electron wavefunction in common use is a single
antisymmetric product (or ``Slater-determinant'') of one-electron
functions (or molecular orbitals, MOs) which are orthonormal linear
combinations of the atomic orbital (AO) basis functions. The expansion
coefficients are determined by minimization of the energy in the Self
Consistent Field 