What is the physical meaning of electrostatic difference potential?

[zhkg7120]

I have a question on the physical meaning of electrostatic difference potential.

I found other expression like electrostatic potential difference or electrostatic potential drop. Do they have the same meaning?

BTW, what is the relationship between electrostatic difference potential and rectification performance?

As far as I can see, the electrostatic potential will linear drop without no rectification, and electrostatic difference potential  is constant. However, on the interface, the electrostatic potential will change nonlinearly, and electrostatic difference potential will also change significantly. Moreover, the region with high electrostatic difference potential value actually play a important role in rectification performance, such as molecular diode.

Thanks!

[Anders Blom]

The electrostatic potential [tex]\phi[/tex] is the solution to the Poisson equation [tex]\nabla^2 \phi=-\rho/\epsilon[/tex], where the [tex]\rho[/tex] is the electron density.

The electrostatic difference potential is the solution to the Poisson equation where on the right-hand side you have the electron difference density, which is the (total) electron density minus the density of the neutral atoms. Partly for technical reasons, the difference potential is the quantity used in the DFT approach in ATK, rather than the full potential.

"Potential difference" is something different than "difference potential" - the words do not commute (as subtraction is non-commutative)

[ams_nanolab]

A positive EDD means a transfer of charge to that region/ atom, so what will a higher value/ lower value of EDP signify? The potential due to which such charge redistribution will take place?

[Jess Wellendorff]

I am not sure it works like that. I would rather say that a high value of the EDP identifies spatial regions where significant charge redistribution has taken place, as compared to the sum of electron densities from neutral and "non-interacting" atoms.

[Anders Blom]

That's correct however the picture is somewhat complicated by the fact that it also includes external potentials, like source-drain bias and gate potentials.

In the 2016 version it will be possible to compute the full Hartree potential. Then there will be a clear mapping between the physical potential and the real-space total electron density.

[ams_nanolab]

Thanks.