Dear R. Rajesh

At first, you should run the SCF part that the cutoff values are so important here. In my book, you can try to reduce the value of the threshold. Some times the max-time can also affect the convergence problems.

Eventually, check the result section and read the crash or error files that may help you.

best regards

It seems you're considering a supercell of BFO with probably too many atoms. To get a fast convergence, I suggest you to use these tags in the &SYSTEM section of your input file:

ecutwfc = 35 ,

noncolin = .true. , ! assuming you include spin-orbit coupling

lspinorb = .true. , ! assuming you include spin-orbit coupling

occupations = 'smearing',

smearing = 'methfessel-paxton',

degauss = 0.02,

and also add these tags in the &ELECTRONS section

conv_thr = 1.0d-8 ,

mixing_beta = 0.2 ,

electron_maxstep = 200 ,

mixing_ndim = 10 ,

I also suggest that you remove the tag related to the number of bands, unless you're really sure what you're doing. For the KPOINTS make sure that the gamma point is considered. The following should work:

K_POINTS automatic

5 5 2 0 0 0

Respected Dr Bahramy,

While thanking for your prompt response, I tried the suggestions but still, the band structure is unable to converge.. for a day about 25 steps are not converging and still hanging. please help me to solve this issue.

Thanks in advance

If you'd like, you can send me your input file and I'll try to take a look into it.

Respected Dr Bahramy,

I am attaching herewith the input file for band structure. Thanks in advance

Dear R. Rajesh ,

This input is for band structure calculation. To get this done, you first need to perform a self-consistent calculation, using CONTROL tag: calculations = 'scf'

Have you already done this?

Respected Dr Bahramy,

yes I have already done that too. pls, find the attachment. please help me to sort out this issue..

Thanks in advance

Do you mean, you successfully converged the scf part?

Yes Dr. Bahramy..

If you have successfully done the scf part. You should be able to do the band calculations without any convergence issue. With the attached input files, I could calculate the band structure for your system without any problem, using the commands

mpirun -np (number of cores) pw.x -npool 4 band.out

mpirun -np (number of cores) bands.x -npool 4 bplot.out

If you still have a problem, then definitely it is related to your SCF calculation.

Respected Dr Bahramy,

Thanks for your prompt response. I will do the process based your input file and get back to you at the earliest. Thank you once again.

Good luck!

Dear Rajesh

First go to Materials progect site and down load CIF file for you materials

Generate input file using Quantum Espresso platform

Run SCF first

NSCF not required but do it

Generate Band in put file

Run pe< Band.in>

Run band command

You will get Bands.dat fine

Open data in Excel

And using origine plot the graph

If not contact to me

[email protected]

How to run band structure calculation of BiFeO3 using quantum espresso with high resolution ?