Conductance calculations for the atomic relay

The resistance of a wire consisting of a line of 3 Mg atoms between two macroscopic metallic electrodes is calculated as a function of the displacement of the center atom laterally out of the line. A displacement of somewhat over 3 Å increases the resistance by a factor of ∼10. This contrasts with the behavior of open-shell atoms: a lateral displacement of the same magnitude of the central atom in a line of Na atoms leads in fact to a small decrease in resistance. © 1998 Academic Press Limited.