ABINIT Discussion Forums

Dear All,

I am calculating the band gap of TiO2 bulk. For the 1×1×1 unit cell, I do the convergence calculations to get the suitable K-point, ecut and so on.
My question is whether I can use these converged parameters to calculate the 2×2×2 unit cell. Should I also do the convergence calculations for the 2×2×2 unit cell. It would be very nice if you could give me some suggestions! Thank you in advance!

Best,

Wang

Ecut is determined by the ions and not the size of the cell, so your converged value of ecut should be fine for the larger
calculation. The good news is that you can probably lower the number of k-points for the larger cell.

Hello,

Your cutoff energies should stay the same (ecut, ecuteps ecutsigx), your k-point grid might be reduced as tetermp mentioned. Concerning the number of bands in the screening and sigma, it should be somewhat linear with the size of the system, so multiplied by 8 in your case.

David