Electrons of different wavevectors from electrode to molecule can be counted?

[Jin-Kyu Choi]

Dear all,

Nowdays, I'm studying electron transport in a molecular junction (two probe system) with semiconducting silicon electrode.
As well-known, the bulk silicon is indirect band gap material (Eg=~1.1eV, direct band gap at Gamma=~3.4eV).

Especially, I'm considering the injection and ejection of electron from Si electrode (left) to molecule (central) and to Si electrode (right).
I'm wondering about how to understand the electron injection and ejection with the concept of band structure for the Si electrode.
With those concerns, I would like to ask few questions and comments:

1. Is it right to think that electron injects from valence band of the Si electrode to the molecule, at which the wavevector of the electron is kept?
   And the electron ejects from the molecule to the conduction band of the Si electrode. In this case, the electron ejects to the conduction band at Gamma point of the Si electrode?

2. As I know, ATK computes only for coherent transport and if it is right the electron transport occurs with the same wavevector?

I probably have some misunderstanding, please give me some correction.

Thank you very much.

[kstokbro]

The wave vector perpendicular to the transport direction is conserved, i.e. the x,y directions. The wave vector in the transport direction is not conserved, only the energy is conserved.

Thus, which bands in the electrodes that are involved, depends on the applied bias. At zero bias transport will always be from valence to valence, and conduction to conduction band, i.e. conserving the energy.