In particular, what are the specific strengths and weaknesses of each kind of theory and how do they complement each other. Finally, suggest a situation or problem where it would be beneficial to apply both levels of theory, one before the other. Very, very rapid. Very reliable for molecules similar to those found in the training set from which parameters were developed. Parameterized against experiment.
Computational effort scales well with molecular size.
Parameterized against experiment. Requires only a few constants for each kind of atom. Requires lots of constants, especially for angle bending and torsions. Hard to extend to new atom types as a result. No wavefunction to analyze.