Construction of Becke's "half-and-half" functional (BHandH) in eq. 1 is justified by a simple approximation to the adiabatic connection formula. The half-andhalf recipe was quickly modified, swapping out LSDA in favor of a generalized gradient approximation (GGA), namely B88 exchange, along with the Lee-Yang-Parr (LYP) correlation functional. A modern version of the half-and-half functional is