(Color online) Examples of atomic structure of the device regions of the Au-benzenedithiol-Au systems in different models as explained in the text. The leads in (a)–(c) are in the (001) orientation while those in (d)–(f) are in the (111) orientation. (a) and (d) are in model A, where the finite cross sections of the leads are indicated. (b) and (e) are in model B, where the frames indicate the supercells for the infinite periodic surface leads. (c) and (f) are in model C, where a nanowire is introduced to connect the molecule to the extended lead; its width and length are indicated: for instance, 7L in (c) means seven-atomic-layer long.
(Color online) Optimized atomic structure of the molecule and the structure of where two three-Au-atom chains are attached (Au–Au distance is fixed at 2.65 Å). The LML systems with the former have been shown in Fig. 1; those with the latter are similar but have a three-Au-atom chain at each contact (model D).
(Color online) Calculated functions for the different LML systems in models A and B [examples of their atomic structures are shown in Figs. 1(a) and 1(b) for (001) orientation, and Figs. 1(d) and 1(e) for (111)]. The width of the leads with a finite cross section and the size of the supercells used for the periodic surface leads are indicated in the legends. Also indicated is the equilibrium conductance .
Transmission function of the pure infinitely long (111)- lead (nanowire). Note the step-function structure because of waveguide effects.
Projected density of states on the molecule for the (111) LML systems with the finite-cross-section lead and the periodic surface lead. Note the large oscillation in the former.
(Color online) curves of the different LML systems with (a) (001) leads and (b) (111) leads [see Figs. 1(a) and 1(b) and Figs. 1(d) and 1(e)], which are calculated from the functions in Fig. 3 neglecting bias-induced effects in . The cross sections of the leads are indicated in the legends.
(Color online) Transmission functions of the LML systems with a nanowire connecting the molecule to the extended lead, as shown in Figs. 1(c) and 1(f). The length of the nanowire and the equilibrium conductance of different LML systems are listed in the legends.
(Color online) Transmission functions of the LML systems shown in Figs. 1(a)–1(e), but with an apex Au atom at each contact, as indicated in Fig. 2. The structures of these LML systems and their equilibrium conductances are indicated in the legends. Note the large resonance peak around the Fermi energy and the similar structures for all the different systems due to the introduction of the additional Au atom at each contact.
Transmission functions of the LML system shown in Fig. 1(b), but with an atomic chain of two (solid line) and three (dashed line) Au atoms at each contact, as indicated in Fig. 2 for the three-Au-atom chain. Note that the resonance peak around the Fermi energy remains as the number of Au atoms in the chain changes.
Article metrics loading...
Full text loading...