Ab Initio Analysis of Electron Transport in Oligoglycines

We study the electrical characteristics of a group of glycine oligopeptides (1-, 3-, 6-, and 9-mers) molecules attached to gold nanoelectrodes using a combined density functional theorysGreen’s function approach. Our procedure considers the applied voltage through the molecule and contacts, recalculates self-consistently the molecular orbitals, Hamiltonian and overlap matrices at each applied voltage, and uses these results to estimate the current-voltage characteristics such that the chemistry of the molecule is fully considered when including the effect of the nanoelectrodes. Our results show that oligoglycines can be used to tailor specific properties for the fabrication of molecular devices and the characteristics may be strongly affected by the few contact atoms addressing the molecule. Oligoglycines show transport behaviors that go from ohmic conductance to Schottky barriers as the length of the oligomers and conformation of the electrode atoms vary.