How to select segments
OldrayHex opened this issue · comments
Hi Lucy,
I have a problem when using your code for my DFT analysis. I can't select a certain segment when I prefer to calculate effective mass along some certain directions in K-paths. I have tried to change the value of "extrema_search_depth" and "energy_range", but it doesn't work. It would be so great if you can give me some advices. Thanks very much.
Sincerely,
Wuliji
Hello Wuliji,
Sure - I'll take a look. Could you share your input files and the Jupyter Notebook / code you are using, telling me on which line(s) you don't get the result you expect?
Lucy
OK, thanks very much. I will send them to you by email just for a moment.
Of course, thank you so much. #
emass_calc.txt
My problem is how to get the information of the more flatter band (at the right side of segment2 in the picture above). I have tried to alter the parameters of "extrema_search_depth" and "energy_range", but it didn't work. If you can teach me how to handle it, I'll be very grateful to you.
Hello @wulijixxx I think the problem might be because you have the same kpoint repeated at each of the special points in k-space (0.5,0,0 and 0,0,0 and 0,0,0.5 and 0.5,0,0.5). Ideally the code would handle this but I haven't got time in the next couple of weeks to sort it out. A workaround might be to manually remove the repeateddata.kpoints and corresponging data.energies and data.occupancies, and to decrease the value of data.number_of_kpoints (or re-run the DFT without the extra kpoints if it's not an expensive calc!). Hopefully the generate_segments will find your segments then...let me know how it goes. Apologies I don't have time to adjust the code now.
OK. I will have a try. Thanks a lot.
@wulijixxx I have just remembered that I added an optional argument to the extrema.generate_segments function. It allows you to manually set an extrema point (specifiying the band index and kpoint index). You can use this to get information about the flatter band. The documentation is here: https://effmass.readthedocs.io/en/latest/extrema.html#effmass.extrema.generate_segments .
If it is not working as expected please let me know.
Hi @wulijixxx how are you getting on? Is the issue fixed?
Hello, I have a problem when using effmass to calculate effective mass of my DFT data. effmass cant determine CBM in band structure and as a result there is no effective mass calculation for CBM. Here I attached the result of effmass calculation. can you help me with this problem?
Thank you
@heessaamm just re-visiting this issue. I think the problem might be with the fermi energy of the system. If the fermi level is incorrect (too high) it will not find any minima below it. You can manually set the fermi level in Settings with Settings.fermi_energy.