Band convergence in the d/dk calculation with occopt=7
Posted: Wed Mar 09, 2011 3:06 am
Dear all,
I'm performing several calculations on phonon frequencies in CdS. Following what Matthieu said in this post, I used occopt= 7 with a low tsmear (0.005 Ha) in order to improve the convergence in the d/dk calculation.
This indeed improved the convergence but triggered another problem: my last two bands are not converged, whatever the number of bands in my calculations (I tried nband=18, 40 and 45). This can be seen on the "res" block in the ouput file:
You can see that the last two bands are not converged, at all.
When I use 18 bands (only filled bands), with occopt=1, the convergence is a bit slower but:
Now all the bands are converged.
Is that a problem?
Thank you for your anwers
Boris
I'm performing several calculations on phonon frequencies in CdS. Following what Matthieu said in this post, I used occopt= 7 with a low tsmear (0.005 Ha) in order to improve the convergence in the d/dk calculation.
This indeed improved the convergence but triggered another problem: my last two bands are not converged, whatever the number of bands in my calculations (I tried nband=18, 40 and 45). This can be seen on the "res" block in the ouput file:
Code: Select all
Mean square residual over all n,k,spin= -4.4444E-03; max= 9.9832E-21
0.0000 0.0000 0.0833 1 8.82866E-21 kpt; spin; max resid(k); each band:
1.51E-21 8.18E-21 4.06E-21 5.17E-21 5.17E-21 4.58E-21 4.58E-21 1.50E-21
1.50E-21 3.00E-21 3.00E-21 1.99E-21 7.97E-21 8.78E-21 8.78E-21 5.62E-21
2.97E-21 2.97E-21 5.66E-21 1.89E-21 7.40E-21 7.40E-21 4.03E-21 1.62E-21
3.26E-21 3.26E-21 3.83E-21 3.83E-21 3.95E-21 6.61E-21 8.08E-21 8.08E-21
1.98E-21 3.94E-21 6.46E-21 6.46E-21 8.51E-21 5.61E-21 5.61E-21 5.73E-21
5.73E-21 8.83E-21 3.64E-21-1.00E-01-1.00E-01
You can see that the last two bands are not converged, at all.
When I use 18 bands (only filled bands), with occopt=1, the convergence is a bit slower but:
Code: Select all
Mean square residual over all n,k,spin= 5.2588E-21; max= 9.9991E-21
0.0000 0.0000 0.0833 1 9.51723E-21 kpt; spin; max resid(k); each band:
3.34E-21 6.98E-21 3.24E-21 8.02E-21 7.93E-21 2.40E-21 8.06E-21 7.28E-21
4.27E-21 3.24E-21 3.57E-21 2.93E-21 8.55E-21 3.72E-21 9.46E-21 9.52E-21
4.04E-21 6.50E-21
Now all the bands are converged.
Is that a problem?
Thank you for your anwers
Boris