The formation (dissociation) of a given molecule from (into) its fragments is a ubiquitous general idea in computational chemistry; the overarching goal is to describe molecular properties from the union of its smaller fragments. In one approach, the total energy of molecule is given by the energy of fragments. This general idea has been extended to the construction of PIPs in order to obtain a PIPs basis describing the energy of the entire molecule without fragmenting the energy. A brief review is given below followed by details for application to C 14 H 30 .