On 5 September 2012 10:22, Jiseok Kim <tube77 at gmail.com> wrote: > Yes. I checked the geometry before and after the 'relax' which looks ok ... > The atomic distance between neighboring atoms about 12A along x-direction > and about 24A along y-direction.. > The vacuum region along x-direction might not be large enough but I > believe it wouldn't be a problem having considered that the 10~15A of > vacuum region usually is accepted. (Please correct me if I'm wrong.) >
I think your forc_conv_thr is just too low, if you want to reach that ridiculous precision you need to reduce the conv_thr and/or increase upscale. I have a couple more observations: 1. why are you using "cg" diagonalization? If the electronic calculation does not converge with the default algorithm, there is probably a problem in your input; changing algorithm will just mask it. 2. why are you mixing ultrasoft (Si) and norm-conserving (H) pseudopotentials? It is not forbidden, but you get the worst of both methods: high wfc cutoff (NC) and high charge density cutoff (US). 3. does it make sense to do vc-relax in a isolated 1D system? Can't the system just rotate if it wants more space? bests regards, and good work -- Dr. Lorenzo Paulatto IdR @ IMPMC -- CNRS & Universit? Paris 6 phone: +33 (0)1 44275 084 / skype: paulatz www: http://www-int.impmc.upmc.fr/~paulatto/ mail: 23-24/4?16 Bo?te courrier 115, 4 place Jussieu 75252 Paris C?dex 05 -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120905/79086103/attachment.htm