Further, suppose that we want each fragment to have no more than a n atoms. Finally, we need to account for the chosen permutational symmetry; that is, any fragment that includes a permuting atom must also include all the other atoms that permute with that atom. (If this rule is not obeyed, the overall basis will not carry the desired permutational symmetry.) To determine the best atoms for each fragment, we start with p 1 , include any atoms that permute with it, and then include other atoms (and those that permute with them) prioritizing those atoms that have the largest data-set Morse values in combination with p 1 . We include all atoms such that the total number of atoms for this fragment is ≤ a 1 . We move similarly through the other fragments, noting that there may be some desirable overlap of atoms between fragments. The Mathematica-based software for calculating the resulting basis deletes possible duplicate polynomials to compact the basis.