Electron Transmission through Modified Benzene
  The renormalization method is applied to investigate the electron transmission properties of a circuit containing a benzene molecule, in which one of the carbon atoms has been modified so as to simulate displacement in position or replacement by another atom. Consideration of the different possible attachments of the leads, and the relative location of the modified atom, results in 9 distinct configurations to examine. For each configuration, the number and locations of anti-resonances, and whether they shift upon variation of the parameters, is seen to be the key to determining the shape of the electron-transmission curve. In particular, those configurations, in which the perturbed atom is not directly attached to a lead, are seen to have the most variation in their structure, compared to pure benzene. 
Dong Qiu and Kenneth W. Sulston
cond-mat.mes-hall