Anchoring group effects in molecular devices: An ab initio study on the electronic transport of a carbon-dimer

The conductance of a molecular device is sensitive to the contact geometry between the molecules and the probing electrodes. Taking a carbon-dimer C2 as an example and connecting it to the electrodes by different linking atoms H, Cu and S, we investigate the anchoring group effect in molecular devices by the first-principles approaches. The results exhibit that, depending on the anchoring groups and the subsequent different metal-molecule chemical bonds, the current varies over more than two orders of magnitude under the same bias. This emphasizes the great importance of the anchoring groups in molecular devices.