https://doi.org/10.1140/epjb/e2008-00458-4
Conductance through atomic point contacts between fcc(100) electrodes of gold
1
Nanoscience Center and Department of Physics, University of Jyväskylä, P.O. Box 35, 40014 Jyväskylä, Finland
2
Department of Chemistry, 40014 University of Jyväskylä, 40014 Jyväskylä, Finland
Corresponding author: a lopez@cc.jyu.fi
Received:
11
August
2008
Revised:
28
November
2008
Published online:
18
December
2008
Electrical conductance through various nanocontacts between gold electrodes is studied by using the density functional theory, scalar-relativistic pseudopotentials, generalized gradient approximation for the exchange-correlation energy and the recursion-transfer-matrix method along with channel decomposition. The nanocontact is modeled with pyramidal fcc(100) tips and 1 to 5 gold atoms between the tips. Upon elongation of the contact by adding gold atoms between the tips, the conductance at Fermi energy EF evolves from G ≈ 3G0 to G ≈ 1G0 (G0 = 2e/h2). Formation of a true one-atom point contact, with G ≈ 1G0 and only one open channel, requires at least one atom with coordination number 2 in the wire. Tips that share a common vertex atom or tips with touching vertex atoms have three partially open conductance channels at EF, and the symmetries of the channels are governed by the wave functions of the tips. The long 5-atom contact develops conductance oscillations and conductance gaps in the studied energy range -3 ≤ E-EF ≤ 5 eV, which reflects oscillations in the local density of electron states in the 5-atom linear “gold molecule" between the electrodes, and a weak coupling of this “molecule" to the tips.
PACS: 61.46.Km – Structure of nanowires and nanorods / 73.23.Ad – Ballistic transport / 73.63.Nm – Quantum wires
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008