Dear Quantumwise experts：
I meet some problem about the convergence of the IV curve of monolayer MoS2. I intent to investigate the influence of irradiation effect on the transport properties of the 2D monolayer by the IV curve change after simply deleting 1S, 1Mo, or 2S as point defects. So the first thing is to choose a proper eletrode for the 2D MoS2 semiconductor. I have tried the doped MoS2 (using the Atomic compensation charges method), or graphene,or 1 T MoS2 as the electrode, but the iv curves all fail to converge at a large bias (for perfect one may above 1V and for defected one may just 0.2V). As it really takes a long time to find the convergence failure when using the DFT method, here I report the problem about the convergence using the Extended Huckel method for a rather faster result. (no appropriate basis set for MoS2 for the Slater-Koster method).
The attached 1T_2H_EH_large_IV.py showes the structure of my study system for the perfect one. As you can see, I have used a very long electrode and a small 0.01V bias change to guarantee the convergence of the IV curve. However it still fails as shown in test1.png (a). I have calculated the Electrostatic Difference Potential curve at bias 0.79V shown in test1.png (b), and it seems the potential near the electrode is still flat. I wonder whether 0.01 V bias change is still not enough or there are problems in my systems.
In second attached EH_doped_zerobias.py, I used the doped MoS2 as eletrodes to see whether this could help the IV curve convergence. However it remains a problem. As shown in test2.png(a), when I found the convergence problem, I lower the bias change to 0.01 V between 0.2V - 0.3V. However it is still trapped at bias 0.26V. Then the previous claculation becomes converged after 7645 steps. However it already takes 7598 steps at 0.26V in test2.png(b), then I have canceled the latter one. It seems the shorter bias does not work in my work. Then I plot the dE\dM\dH change in test3.png(c) , it seem the convergence progress becomes sharply. So how can I determine the maximum steps during each bias change as it is impossible to predict its tendency.
I wonder whether there are parameters-setting problems in my system or the total concept of my study is wrong? Any suggestion or comment will be appreciated.
