State-averaged multiconfiguration self-consistent

State-Averaged Multiconfigurational Self-Consistent Field Method... 

Initially only state-averaged multiconfigurational self-consistent field (SA-MCSCF) wave functions could be treated but subsequently the algorithm was extended to treat general multireference configuration interaction (MRCI) wave functions. Here x(X) denotes the space fixed frame coordinates of the A electrons nuclei) and < >/ is one of A electronic... 

Cl = configuration interaction SA-MCSCF = state averaged multiconfigurational self-consistent field. 

A more balanced description thus requires multiconfiguration self-consistent field (MCSCF)-based methods, where the orbitals are optimized for each particular state or optimized for a suitable average of the desired states (state-averaged MCSCF). In semiempirical methods, however, an MCSCF procedure is normally not required due to the limited flexibility of the minimal valence atomic orbital basis commonly used in these methods. Instead, a multireference Cl method including a limited number of suitably chosen configurations will be appropriate. 

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