Renormalized molecular levels in aSc3N@C80molecular electronic device

We address several general questions about quantum transport through molecular systems by an ab initio analysis of a scandium-nitrogen doped $C_{80}$ metallofullerene device. Charge transfer from the ${\mathrm{Sc}}_3\mathrm{N}$ is found to drastically change the current-voltage characteristics: the current through the ${\mathrm{Sc}}_3\mathrm{N}@{\mathrm{C}}_{80}$ device is double that through a bare $C_{80}$ device. We provide strong evidence that transport in such molecular devices is mediated by molecular electronic states which have been renormalized by the device environment, such as the electrodes and external bias $V_b.$ The renormalized molecular levels and main transmission features shift in energy corresponding to half the applied bias voltage. This is also consistent with our finding that the voltage drops by $V_b/2\mathrm{}$ at each molecule/electrode contact.