Using the MCSCF wave function as the initial guess can improve the success probability dramatically, even just a few CSFs.
The method can be generalized to general MRCI scheme and the entire potential energy surface can be explored for ground state and excited states.
Instead of starting from a single element as in the HF wave function, MCSCF method starts from a small matrix. This makes the evolution safer and faster.
The idea can be generalized to Finite element method and any numerical method.
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