Solids modeled by ab initio crystal field methods. Part 14. Structure of four polymorphic forms of sulfapyridine

Abstract

SUMMARY The structure of sulfapyridine in the gas phase and in four different crystal forms was studied with ab initio Hartree‐Fock methods. The crystalline environment of the polymorphs II, III, IV and V was described by a point charge model consisting of stockholder or Mulliken charges. The calculations were performed with the 6‐31G basis set for the hydrogen and first row atoms and the 6‐6‐31G basis set for the sulfur atom. In the SCF step of the calculations the multiplicative integral approximation (MIA) was used. The theoretical results for polymorph II, III and IV are in good agreement with the experimental data, but the point charge model failed for the optimization of polymorph V which contains two different molecules in the unit cell. ©1997 by John Wiley & Sons, Ltd.