Multiconfigurational energy computational procedure

With only a few electrons outside a closed shell, the above equations may be solved iteratively in essentially the same manner as the Hartree-Fock equations. Usually an algebraic approximation is used in which every is expressed as a linear combination of basis functions as in Section 6.2 and this leads to matrix equations that are more suitable for computational purposes. The actual techniques of optimization are similar to those used in multiconfiguration versions of MO SCF theory (Chapter 8) the more rapidly convergent procedures require also second derivatives of the energy expression, but these may be obtained in the same way as the first derivatives. 

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