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(Color online) Adsorption sites of the Co-1 molecule on gold surfaces. (a) Adsorption between gold nanowires at hollow site. (b) Top view of gold 001 surface. Circles indicate gold atoms while crosses mark adsorption sites-hollow , bridge , and top . (c) Adsorption on an apex Au atom. (d) A small island protruding out of both electrodes where Co-1 is adsorbed. Gray, white, dark gray, medium gray, and light gray denote carbon, hydrogen, cobalt, sulfur, and gold atoms, respectively.
(Color online) Transmission spectra of Co-1 with different adsorption geometries; solid and dashed lines denote the spin up and down components, respectively. [(a)–(c)] Hollow, bridge, and top sites of (001) oriented rodlike gold leads [as shown in Figs. 1(a) and 1(b)]. (d) Transmission for adsorption on top of an apex gold atom [Fig. 1(c)]. (e) The transmission function of Co-1 adsorbed at the hollow site of an infinite (001) surface. The surface is covered with a monolayer of Co-1 by repeating the structure shown in Fig. 1(a). (f) Transmission of Co-1 attached to a small island protruding from a (001) surface [Fig. 1(d)]. [(g)–(h)] Transmission for adsorption at the hollow and top sites of an infinite (111) surface. The surface is covered with a monolayer of Co-1 with a cell.
(Color online) Surface of constant local density of states for Co-1 at the Fermi energy. [(a) and (b)] Spin up and down components, respectively, for (001) hollow site. [(c) and (d)] Spin up and down components, respectively, for Co-1 adsorbed on top of apex gold atoms.
(Color online) Transmission spectra of Co-0 adsorbed (a) at the (001) hollow site and (b) on top of apex gold atoms. Solid and dashed lines denote spin up and down components, respectively. Note the much greater sensitivity to contact geometry in this molecule than for Co-1 (compare to Fig. 2).
Ratio of the spin up to spin down transmission for the eight cases shown in Fig. 2. is the value at the chemical potential; is the largest value, occurring at an energy around where the spin up transmission peaks. , , , , , and denote adsorption on a (001) lead in the case of a hollow site, bridge site, top site, apex gold, hollow site of an infinite surface, and hollow site of a protruding island, respectively. and denote adsorption on an infinite (111) surface at the hollow and top sites, respectively.
Charge difference, with respect to a reference configuration, on the sulfur atoms , sulfur plus spacer atoms , and cobaltocene moiety . The reference configuration is adsorption at the hollow site of (001) oriented nanowire leads. The subscripts , , and refer to bridge, top, and apex adsorption sites; and refer to the infinite surface leads and islands on nanowires, respectively; and denote hollow and top adsorption sites on a (111) surface. Co-1 and Co-0 denote molecules with and without spacers, respectively. The values are obtained via Mulliken population analysis. The minus sign denotes electron loss (transfer from the molecule to the lead).
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