Induced ring currents in polymerized C₆₀ and C₇₀ molecules

Ring currents induced by the presence of an external magnetic field are investigated in polymerized fullerenes. Linear chains (with closed ends) containing up to ten C₆₀ molecules joined along their 2-, 3-, and 5-fold axes of symmetry, are studied using a π-electrons Hückel model in conjunction with the London approximation. We also investigated linear chains built by connecting C₇₀ fullerenes along the 5-fold axis. Ring current patterns as well as ring current magnetic susceptibilities were calculated. Extremely large ring currents are obtained in polymerized molecules when a specific number of molecules are contained in the linear system. It has been found that C₇₀ chains exhibit large ring currents only for an even number of molecules whereas C₆₀ chains show large rings currents for a particular number of molecules n = 3, 6, 7, 10. Finally, the role played by the curvature on the magnetic response of these polymerized systems is discussed.