Using the nonequilibrium Green’s function combined with the density functional theory, we investigate the dynamic conductance of atomic wires consisting 4–9 carbon atoms in contact with two Al(100) electrodes. Our numerical results show that in addition to the dc conductance, both the real part and imaginary part of dynamic conductance show oscillatory behaviors for even-odd number of carbon atoms at low frequencies. Interestingly, the dynamic part of the ac conductance depends only on the parity of the number of carbon atoms $n$, i.e., whether $n$ is even or odd. These oscillations of dynamic conduction can be understood by analyzing the average transmission coefficient $T_{\text{av}}$ and the global density of states.

• Received 8 January 2009

DOI:https://doi.org/10.1103/PhysRevB.79.155117