Theoretical investigation of thionyl and sulfuryl dihalide structures using density functional theory methods

Abstract

The geometries of small polar molecules that contain S, O, Cl, and F were computed by both ab initio and density functional theory (DFT) methods. A large number of the DFT methods (hybrid, local, and non-local) were tested and the computed geometries were compared with experimental and ab initio results. By using a model basis set (6-311G(d)), two DFT methods (BHandH and XAP86) were selected as being appropriate for modeling these and similar systems. Considering the modest computational time, they should be methods of choice for computing the geometries of larger organic molecules that contain parte built from electronegative elements such as S, O, Cl, and F. This is a very important finding since two widely used ab initio methods (RHF and MP2) fail to generate satisfactory geometries.