I am looking for the electron transport study in a single gold atom, like the system of single carbon atom shown in transiesta paper by Nick Papior et al. Computer Physics Communications, 212, 8-24, (2017).
I have connected the gold atom with linear chains of silver atoms, and has studied the effect of symmetric variation of Ag-Au separation. (Figure attached here)
I am getting transmission peaks at energy slightly below the 4eV, while there is no energy level in the discrete levels of single gold, and the PDOS plot. Moreover, the position of a peak near the Fermi level is not consistent with the position of the discrete system.
To mention these calculations are done for zero bias, so in principle, resonant tunneling is expected.
Also, as a result of increasing Ag-Au separation, there is more suppression of transmission in some channels, while some attain the same height. Last subplot show discrete levels of gold atom.
I have these queries:
(a) Why is transiesta giving the peaks where there is no energy level?
(b) Is the separation in peaks here describe the weak Ag-Au coupling?