For this reason, and since some description of NCIs relevant for PL binding is clearly crucial for predictive purposes, electronic structure calculations are mostly combined with additional computational techniques used for describing the dynamic, continuous relationship between PL pairs that leads to biochemically-significant (active-site) binding. In this manner, electronic structure calculations are performed on static structures, which are assumed to represent crucial events in the PL binding process (see Ref. for a recent, comprehensive review). It is generally assumed, for instance, that the actual biochemically-significant binding event -taking place in the protein's active site -must incorporate some description of noncovalent binding factors. Thus, one common piece of information on PL interactions provided by electronic structure methods corresponds to the PL binding energy -calculated as the energetic difference between the bound PL structure and its underlying protein and ligand structures found at infinite separation (Eq. 1):