The question of screeing layers including electrode copies

[wot19920302]

Dear Quantumwise staffs
         We know from ATK ver.10.8 , the screening layers include electrode copies : http://quantumwise.com/documents/tutorials/latest/UpgradeGuide/index.html/chap.upgrade.html#sect1.upgrade.twoprobe. Functions of electrode copies is extend screening areas to make electrostatic difference potential smoothly apporach potentials of electrodes, right? But what about electrostatic difference potential always drop along the whole central region such as Fig.1? In Fig.1, electrostatic difference potential is calculated by 0V.nc and 0.5V.nc. Can we use datas from 0.5V.nc to get correct results?
         Best

[Anders Blom]

Either your central region is way too short, or there is no scattering taking place (perfectly periodic system), or something else. One can only guess without knowing the actual system geometry...

[wot19920302]

uh,it is perfect 1D periodic system. I know for  such system, electrostatic difference potential along the central region is hard to approach potentials of electrodes. But transmission spectra can be analyzed by overlaps of energy bands of electrodes like this paper :Role of Symmetry in the Transport Properties of Graphene Nanoribbons under Bias. Can we use these datas?
 Best

[Anders Blom]

Although that paper contains some interesting results, I think the authors of that paper should have read some basic material about the Landauer-Buttiker approach. If they did, they would realize that computing the coherent, elastic transmission at finite bias of a perfectly periodic structure (as you are trying also) is a waste of time. For details on this point, which has been addressed multiple times on this forum (but I understand it's a difficult point), see https://quantumwise.com/forum/index.php?topic=3178.msg14792#msg14792.