Machine calculations for polyaryleneimide chain conformations and packing in the crystalline zones; the combination of the atom-atom potentials method with X-ray structural analysis☆

Abstract The criterion of correctly selecting the optimal molecular conformations present in the crystalline zones is the agreement of calculated with the experimental diffraction picture, but even this will be unreliable because of the small number of reflexions present in the latter. An optimization based on the energy is not always reliable because of the approximations made about the absolute energy. The method proposed here imposes two conditions on the looked-for molecular conformations, namely a small, not necessarily minimal energy, and an agreement of the X-ray pictures. The algorithms used to solve this problem are based on the suggestions of I. M. Sobol for optimizing the program planning.