Dear VASP admin,
We tried to model a spinel cobalt structure with conventional and primitive cells. After full relaxation, we performed single point calculation using HSE06 to get the band gap.
However, we found the structure to be metallic with the primitive cell while it is semiconductor with the conventional cell.
In the case of the conventional cell, the electronic convergence was down to 1E-03 at step 25, then back to 1E+00 and start to reconverge again until the electronic steps limit "60". Then, we recontinue with wavecar and the calculation converges with a bandgap of about 0.8 eV.
In the case of the primitive cell, the calculation is converged in 28 steps with a metallic behavior.
-Why such different results from both cases, which one we should rely on?
-and what happened with the conventional cell's run, is it normal to converge up to some degree then return back and reconverge again?
Many thanks in advance,
Ibrahim