additional information:
I checked the .log file for some bias points. e. g. at bias 0.18V, 0.21V and 0.24V. Because of the size limit, I cannot attach the .log files. Instead, I post here the band energy (E) and the difference (dE) and Hamiltonian matrix elements (dH) of the last 30 SCF cycles.
For bias at 0.18V, it did not converge. The band energy (E) and the difference (dE) and Hamiltonian matrix elements (dH) were like below--
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| 170 E = -651.798 dE = 4.044902e-02 dM = 1.038161e-01 dH = 1.303229e+00 |
| 171 E = -651.82 dE = 6.973168e-03 dM = 3.794980e-02 dH = 1.271307e+00 |
| 172 E = -651.72 dE = 2.003298e-02 dM = 6.139546e-02 dH = 1.193302e+00 |
| 173 E = -651.622 dE = 1.387764e-02 dM = 4.281661e-02 dH = 1.060334e+00 |
| 174 E = -651.849 dE = 7.970397e-03 dM = 5.317894e-02 dH = 1.356581e+00 |
| 175 E = -652.08 dE = 1.045167e-02 dM = 5.989330e-02 dH = 1.617708e+00 |
| 176 E = -651.601 dE = 1.316316e-02 dM = 8.908298e-02 dH = 1.117005e+00 |
| 177 E = -651.484 dE = 7.704034e-03 dM = 2.618570e-02 dH = 1.053042e+00 |
| 178 E = -651.487 dE = 7.129752e-03 dM = 3.691645e-02 dH = 1.139085e+00 |
| 179 E = -651.27 dE = 1.189893e-02 dM = 6.756393e-02 dH = 9.374030e-01 |
| 180 E = -651.139 dE = 1.491213e-02 dM = 9.123284e-02 dH = 7.960077e-01 |
| 181 E = -651.049 dE = 4.868724e-03 dM = 1.342229e-02 dH = 7.873335e-01 |
| 182 E = -651.669 dE = 3.652773e-02 dM = 2.233291e-01 dH = 1.450075e+00 |
| 183 E = -651.298 dE = 4.110651e-02 dM = 2.106917e-01 dH = 8.166819e-01 |
| 184 E = -651.155 dE = 2.307643e-02 dM = 9.002607e-02 dH = 5.569482e-01 |
| 185 E = -651.34 dE = 1.438901e-02 dM = 5.903590e-02 dH = 7.863402e-01 |
| 186 E = -652.389 dE = 9.476284e-02 dM = 3.559915e-01 dH = 2.182220e+00 |
| 187 E = -651.345 dE = 8.504621e-02 dM = 3.339246e-01 dH = 9.054757e-01 |
| 188 E = -651.492 dE = 1.757176e-02 dM = 7.981000e-02 dH = 7.091878e-01 |
| 189 E = -651.795 dE = 1.554410e-02 dM = 1.248392e-01 dH = 1.179052e+00 |
| 190 E = -651.612 dE = 1.267145e-02 dM = 1.126878e-01 dH = 9.885518e-01 |
| 191 E = -651.03 dE = 3.537401e-02 dM = 2.072327e-01 dH = 1.250047e+00 |
| 192 E = -650.925 dE = 3.590851e-02 dM = 1.609478e-01 dH = 1.138320e+00 |
| 193 E = -650.759 dE = 1.579183e-02 dM = 7.361792e-02 dH = 8.462947e-01 |
| 194 E = -651.121 dE = 1.692964e-02 dM = 1.240033e-01 dH = 1.274886e+00 |
| 195 E = -650.785 dE = 2.565320e-02 dM = 1.908225e-01 dH = 8.584790e-01 |
| 196 E = -650.836 dE = 2.554568e-02 dM = 1.201435e-01 dH = 8.476001e-01 |
| 197 E = -650.806 dE = 6.826299e-03 dM = 2.917748e-02 dH = 8.480110e-01 |
| 198 E = -650.897 dE = 1.317645e-02 dM = 7.354966e-02 dH = 9.450469e-01 |
| 199 E = -651.211 dE = 1.030746e-02 dM = 5.507171e-02 dH = 1.119665e+00 |
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While for bias at 0.21V, it looks like that the calculation became converged suddenly after the 64th SCF cycle.
| 56 E = -15.4467 dE = 2.979340e+00 dM = 8.417096e-02 dH = 5.858600e+01 |
| 57 E = 0.00635501 dE = 3.844430e+00 dM = 1.130846e+00 dH = 4.368325e+01 |
| 58 E = -12.5127 dE = 5.390223e+00 dM = 1.930463e-01 dH = 4.105452e+01 |
| 59 E = 0.00310733 dE = 5.390057e+00 dM = 1.930700e-01 dH = 1.893029e+01 |
| 60 E = 0.0764951 dE = 1.652323e-02 dM = 1.084730e-02 dH = 1.828765e+01 |
| 61 E = 0.00809108 dE = 1.658976e-02 dM = 2.095044e-02 dH = 1.616004e+01 |
| 62 E = -0.0803081 dE = 1.399932e-02 dM = 1.549542e-03 dH = 1.511367e+01 |
| 63 E = -7.52488 dE = 1.594457e+00 dM = 8.609775e-01 dH = 4.567215e+00 |
| 64 E = -0.0266777 dE = 1.599368e+00 dM = 8.625010e-01 dH = 3.453103e+00 |
| 65 E = -0.0147232 dE = 2.538757e-03 dM = 6.304485e-04 dH = 3.877150e+00 |
| 66 E = -0.0190753 dE = 7.759180e-04 dM = 3.252699e-05 dH = 3.630938e+00 |
| 67 E = -0.0104623 dE = 1.682583e-03 dM = 2.314317e-04 dH = 2.961721e+00 |
| 68 E = -0.0225712 dE = 2.457818e-03 dM = 4.489571e-04 dH = 2.611185e+00 |
| 69 E = -0.0126081 dE = 2.011628e-03 dM = 3.855940e-04 dH = 2.890064e+00 |
| 70 E = -0.0143453 dE = 3.408293e-04 dM = 1.152833e-04 dH = 6.236782e-01 |
| 71 E = -0.0160083 dE = 3.413112e-04 dM = 8.456062e-05 dH = 1.250041e-01 |
| 72 E = -0.015811 dE = 4.175172e-05 dM = 1.444087e-05 dH = 6.493140e-02 |
| 73 E = -0.0155582 dE = 5.125033e-05 dM = 7.791216e-06 dH = 5.607342e-02 |
| 74 E = -0.0158437 dE = 5.850811e-05 dM = 1.320131e-05 dH = 7.990641e-02 |
| 75 E = -0.0158074 dE = 7.601333e-06 dM = 5.263977e-06 dH = 3.829023e-02 |
| 76 E = -0.0156398 dE = 3.460024e-05 dM = 7.400740e-06 dH = 3.973113e-02 |
| 77 E = -0.0157361 dE = 1.943634e-05 dM = 3.812808e-06 dH = 2.234545e-02 |
| 78 E = -0.0156691 dE = 1.358503e-05 dM = 2.976237e-06 dH = 1.309541e-02 |
| 79 E = -0.0156911 dE = 4.653795e-06 dM = 1.348542e-06 dH = 4.449373e-03 |
| 80 E = -0.0156964 dE = 1.072482e-06 dM = 2.929692e-07 dH = 1.736597e-03 |
| 81 E = -0.0156972 dE = 1.891888e-07 dM = 2.617146e-08 dH = 5.071357e-04 |
| 82 E = -0.0156962 dE = 2.085112e-07 dM = 5.349786e-08 dH = 1.551410e-04 |
| 83 E = -0.0156962 dE = 5.215664e-09 dM = 2.899879e-09 dH = 3.090518e-05 |
| 84 E = -0.0156962 dE = 1.405080e-08 dM = 3.694223e-09 dH = 1.070665e-05 |
| 85 E = -0.0156962 dE = 4.027533e-11 dM = 1.433165e-11 dH = 1.021141e-05 |
| 86 E = -0.0156962 dE = 2.061471e-11 dM = 8.844481e-12 dH = 9.864005e-06 |
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And for bias at 0.24V, since the calculation got converged at 0.21V, it got converged very quickly after just one SCF cycle. However, i don't think the current obtained is correct.
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| 0 E = -92.9128 dE = 2.177833e-07 dM = 1.447770e-06 dH = 1.010501e-06 |
| 0 E = -92.8365 dE = 6.841815e-07 dM = 5.734264e-06 dH = 6.902065e-07 |
| 0 E = -0.0156952 dE = 1.784481e-07 dM = 1.012187e-08 dH = 7.222276e-09 |
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