Electron tunneling barrier in DFT

[Mancho]

Hello all,

I'm getting confusing about what to consider as a barrier for electron tunneling in DFT. What I'm doing is looking at the xy plane averaged effective potential, i.e. the potential that electrons feel. This potential in PAW formalism is composed of three terms: V_Hartree+Vxc+Vbar, where V_Hartree is the electrostatic potential, Vxc-exchange correlation, Vbar - unphysical correction. My system is periodic in xy and non-periodic in z. As I understand, if there is a barrier, effective potential should go a bit over the Fermi level. I don't see this in my case. What I encounter in some papers is that they look at only electrostatic(Hartree) contribution. If I plot only electrostatic potential + Vbar correction then there is some portion of plot above Fermi level.

So, which one can be considered as a tunneling barrier, total effective potential or only electrostatic?

Thank you for any help.

 

[eljose79]

Thank you for your question regarding the consideration of barriers for electron tunneling in DFT. In DFT, the effective potential can be composed of several terms, as you mentioned: VHartree, Vxc, and Vbar. It is important to note that the effective potential is not a physical quantity, but rather a mathematical construct used to describe the behavior of electrons in a system. Therefore, it is not necessary for the effective potential to go above the Fermi level in order for tunneling to occur.

In terms of identifying a barrier for tunneling, it is important to consider the total effective potential, as it includes all contributing terms. However, it is also useful to examine individual terms, such as the electrostatic potential, in order to gain a better understanding of the overall behavior of electrons in the system. In some cases, the electrostatic potential alone may be a good indicator of a barrier for tunneling, but it is always best to consider the total effective potential to get a more complete picture.

I hope this helps clarify your confusion. If you have any further questions, please don't hesitate to ask. As scientists, it is important to always critically analyze our results and consider all contributing factors in order to accurately interpret our data. Best of luck in your research.