I am relatively new and interested in the field of theoretical chemistry. I just stumpled across the Klopman - Salem equation (https://en.wikipedia.org/wiki/Klopman-Salem_equation).
In daily life, I only use DFT for bonding energies and I also do not find too many papers about the Klopman - Salem equation, why? (There is not even a pre-defined tag for this equation on stackexchange.)
What are the advantages and disadvanatges of this theory? Are there any theories, that improved this concept ?