Dear Mehmet Topsakal, I tried with a lower ecutwfc (=20 Ry) and the problem goes away ! So it's a memory issue (as Paolo suggested) ! Thanks a lot. If I may I'd like to ask the following question in this regard: 1. As I'm interested in band gap calculation and the calculations (e.g. band gap) need to be converged with respect to both q-points and ecutwfc, should I first set a lower ecut and check convergence with q-points or should it be the other way 'round?
2. As you said "If you are interested only in DOS, you can use smaller cutoff even if you are using NC pseudopotentials." ... It may sound stupid to ask but considering me as a newcomer in this field can you please explain why one can get away with a lower ecut when calculating dos (or band gap through it) even when using NC PPs. Thanks in advance. Rajdeep Banerjee Ph. D. student Theoretical Sciences Unit Jawaharlal Nehru Centre for Advanced Scientific Research Bangalore, India -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20140503/3f856392/attachment.html