Conduction through single Mg and Na atoms linking two macroscopic electrodes

Physical Review B - Condensed Matter and Materials Physics

Volumn 55, Issue 7, 1997, Pages 4113-4116

  Lang, N ^a  

^a IBM T J WATSON RESEARCH CENTER   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 0000888925     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.55.4113     Document Type: Article

References (30)

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4. Note that a drawn-wire experiment done in the scanning tunneling microscope or in a break junction, where the electrodes are linked by a thin wire which at its narrowest point may consist of just one atom, represents a different geometry from that envisioned here. Cf. C. J. Muller, J. M. Krans, T. N. Todorov and M. A. Reed, Phys. Rev. B 53, 1022 (1996).
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19. This is approximately the calculated bond distance for the case in which only one electrode is present [see N. D. Lang and A. R. Williams, Phys. Rev. B 18, 616 (1978)]. We do not try to calculate the equilibrium bond length for the two-electrode case because our results are not very sensitive to its exact value (see Fig. 5); in any case our aim is to study the conductance as a function of atom-surface distance.
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29. It might be thought that for such a narrow resonance, it would be necessary to take account of the fact that the effects of the screened repulsion energy U between two electrons in the valence shell are not adequately taken into account in the local-density approximation used here. It is however shown by Y. Meir, N. S. Wingreen, and P. A. Lee [Phys. Rev. Lett. 70, 2601 (1993)] that for a similar problem, the Kondo peak at the Fermi energy gives rise to a linear-response conductance of (Formula presented)/(πℏ) (zero temperature, zero magnetic field). In this connection, it is also interesting to estimate U for our problem. It can be approximated by subtracting from the difference between the ionization potential and the affinity energy of the free atom (I-A) the interaction energy of one electron midway between the electrodes with the image potential due to a second electron at the same position. (Cf. A. C. Hewson and D. M. Newns, Proceedings of the 2nd International Conference on Solid Surfaces [Jpn. J. Appl. Phys. Suppl. 2, 121 (1974).]) Using the expression for this image potential given in, e.g., W. R. Smythe, Static and Dynamic Electricity (McGraw-Hill, New York, 1950), p. 203, together with the image plane position given by N. D. Lang, Phys. Rev. B 7, 3541 (1973), it is found that U⩽0 for electrode spacings up to 11.4 bohrs (D=2.7 bohr) and that U increases to 1.6 eV for the spacing of 16 bohr (D=5 bohr) used for Fig. 2.
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