Dear Yusufm ecutwfc and ecutrho depend only on the hardest of the pseudopotentials used for the atoms in the molecule or the crystal. If your molecule is C32 and have no other elements, you can make tests with a C2 (which does not exists, I guess), and the cutoffs for C32.
Anyway, if your are going to calculate something that it is not the total energy or the DOS, let's say, the phonons, or the Raman spectrum, it is reasonable that you test the effect of the cutoff first on C2 and then on C32. ---------- Mensaje reenviado ---------- From: Yusuf Zuntu <yz...@yahoo.com> To: PWSCF Forum <pw_forum at pwscf.org> Cc: Date: Wed, 26 Sep 2012 03:15:32 -0700 (PDT) Subject: [Pw_forum] ecutwfc convergence Hi, I need clarification on kinetic energy cutoff. I have a system comprising 32 carbon atoms. Am I to consider total 32 carbon atoms in convergence w.r.t kinetic energy cutoff scf calculation or the two carbon atoms in the unit cell. Thank you for anticipated reply. Yusuf -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120926/ebeb7ceb/attachment.htm