hope you are doing well. I am trying to study the electronic properties of ZnO doped with transition metals (Co, Ni, Fe) using DFT calculation, I am a beginner on DFT calculation using quantum espresso. After running multiple test with increasing the 'ecutwfc' (kinetic energy cutoff for wavefunctions) and 'conv_thr' (convergence threshold) in my input files I get almost the same total energy.

I want to know please how can I make sure that my SCF calculation are correct?

Thank you for your help.

  • $\begingroup$ All of these metals will really want hubbard corrections. Make sure your U values are reasonable for your desired property. $\endgroup$ Jan 26, 2021 at 15:45
  • $\begingroup$ I guess the point is more basic. If you are running multiple SCF calculations with increasing values of energy cutoffs, and convergence threshold, we do expect you to get similar results, since the simulation is converged. $\endgroup$ Feb 1, 2021 at 21:15

1 Answer 1

  • First, make sure that the structure is correct.
  • Second, make sure that the structure is relaxed.
  • Third, make sure that all the parameters in your input card are reasonable and the used pseudopotentials are matched with your structure.
  • Fourth, make sure that the self-consistent loop is complete, namely, the convergence threshold of the electronic step is reached.
  • Fifth, compare the total energy with other published results or the electronic structure (band structure/density of states) based on your converged charge density.
  • $\begingroup$ One question here related to above > what is convergence threshold here and how it is increased with input files any specified tag in INCAR for this ? Related to ENCUT it is clear that by increasing the value of ENCUT , SCF calculations can be done and by observing the different values of total energy in output or same value of total energy in each run. Please correct me if I am wrong here. $\endgroup$
    – Shalini
    Feb 28, 2021 at 16:19

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