the reliability of Huckel method on the calculation of IV curve

[lknife]

Dear experts,

Who can tell me something about the reliability of the IV curves calculated using ATK SE: Extended Huckel method?

It's much faster than DFT method as calculating the IV curve of devices. In many cases, it's almost mission impossible to use DFT methods to calculate the multi-points IV curves for a device with many atoms on a local computer, even on a small computer cluster. Thus, ATK SE: Extended Huckel method could be the only choice if there is no suitable Slater-Korster basis set for a particular system.

However, I want to know the difference between the results calculated using DFT or Huckel method. Who can give me some comments on the reliability of the transmission spectrum calculated using Huckel method? or tell me where to find such information?

Thank you very much for your time!

[lknife]

Dear all,

Attached is the IV curve calculated using GGA method and the .py file for this calculation. There are some fluctuations at large bias region. Can anybody here help me to find out the problems in my parameter settings? Is the fluctuation caused from the insufficient  "Energy resolution" or "k point sampling along B direction" in IV block?

Thanks a lot for anybody who is willing  to hep me!

[Anders Blom]

Only one way to find out - add more. This is a job that always has to be carried out, there is no magic number that is know to be "enough" for any particular system, you always have to converge the settings by adding more points (in k and energy) until the results do not change.

[lknife]

Thank you very much for your reply! I'll do as you suggested.

[Petr Khomyakov]

Regarding the extended Huckel method (EHM) vs DFT approach, in the best case scenario the I-V curve obtained with EHM will be as accurate as the electronic structure of the system calculated using the EHM. So, you should first investigate, e.g., whether the electronic or band structure of your electrode materials and central region region is accurately given by the EHM, i.e., you should benchmark it against the DFT-calculated electronic structure. I note that this does not guarantee accurate I-V curves, as the properties of the interface between the electrode and central region system might not be described by the EHM with the DFT accuracy.

[lknife]

Thank you very much for you reply!

It's really a hard work on the simulation of materials, not simply setting some parameters and running the calculation. There are a lot of things to do to get the reliable results.

Thank you again for your kind help!