We simulate the spin-flip current and transmission function through rings containing elements with a spin-orbit interaction. In a previous study (J. Chem. Phys. 123 (2005) 204714) we predicted that such a system can show spin-birefringence, i.e., a spin current polarized parallel to the molecular axis can flip its direction due to a phase lag due to the spin-orbit interaction. Here we demonstrate the effect in a semi-empirical extended Huckel theory (EHT) molecular simulation. The ring systems studied are naphthalene-bitellurium, gold-porphyrin, and cyclometallated chlorogold, connected to polyacetylene. (C) 2009 Published by Elsevier B.V.