Expansion of the spin-coupled wavefunction in Slater determinants

SummaryThe expansion of the spin-coupled wavefunction in Slater determinants constructed from nonorthogonal spin-orbitals is discussed. It proves possible to generate from cofactors of the appropriate overlap matrix all the density matrices, up to fourth order, required for the variational optimization of the wavefunction. The computational effort inherent in this ‘super-cofactor’ strategy scales in a very acceptable manner with the number of electrons.

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