Theoretical study of the thermochemistry of sulfur molecular crystals II. Lowest energy allotropes of polymeric ω-sulfurs

摘要: Extended Huckel theory (for the repulsive part of energy) and a method derived from classical perturbation expansions long-range attractive were combined adequate parametrization has been set up in Part I. In this first series, tested with success on ω-sulfur an example two interacting helices. Here, we apply to determine lowest energy conformations for all 1D, 2D real 3D structures polymeric ω-sulfurs considered our structural hypotheses. We examine how considerations intermolecular interactions can lead reliable information. Of course, dispersive (attractive) (including dipole-dipole, dipole-quadrupole three-body terms) is necessary quantitatively stability these sulfur structures. find that ω2-sulfur more stable than ω1-sulfur, where each helical chains built three-atom unit cell. For both allotropes, calculated enthalpy sublimation good agreement experimental values.