Mechanical properties and electrical conductance of different A1 nanowires submitted to an homogeneous deformation:: a first-principles simulation

The evolution of the structure and conductance of different Al nanowires subject to a tensile stress has been studied by first-principles total-energy simulations combined with the non-equilibrium Keldysh Green's function approach for transport. Our calculations show the correlation between discontinuous changes in the total energy (associated to changes in the bonding structure of the nanowire) and abrupt modifications of the conductance as the nanowire develops a thinner neck, in agreement with the experiments. In spite of the quite different initial configurations and behaviour for some of the wires, in all the cases we obtain the same structure for the nanocontact during the last stages of the deformation process. The dimer geometry we have found for the nanocontact structure before the final breaking nicely reproduces the characteristic increase of the conductance in the last plateau and the presence of three conducting channels, one with a dominant contribution, giving the total conductance close to the quantum of conductance found in the experiments. (C) 2004 Elsevier B.V. All rights reserved.