Metal-insulator transition of elemental iodine under pressure

Bersohn proposed a model of two-dimensional 5p-electron delocalization for crystalline iodine, which was subsequently fully examined by Rosenberg. In the present work, this model is examined as a function of pressure, by generalizing Rosenberg’s assumptions. It is shown to afford a natural explanation for the formation of a quasi-two-dimensional system for pressures greater than 21 GPa, recently observed by Mössbauer spectroscopy.