Dear all, I have a question about cutoff convergence of total energy. I run some QE calculations on Silicon bulk with hybrid functional, and I found that, fixing the geometry and the number of k/q-points, total energy doesn't monotonically decrease with the increase of the cutoff. Indeed, there are some cutoff values which give a poorer description, in terms of total energy, then some lower cutoff values. I didn't change default convergence parameters. I stress that each simulation is different ONLY for the cutoff value. Now my question is: in your opinion, which is the main source of error? Is it the 30% default mixing value, the finite number of k/q-point, the really high number of operations involved in the calculations that afflict the precision, or something else? I ask this because hybrid calculations are pretty long, and to test every possible source of error would require a great amount of time.
Thanks for the attention, Francesco Macheda Student at Pisa University
_______________________________________________ Pw_forum mailing list [email protected] http://pwscf.org/mailman/listinfo/pw_forum
