> Hi everyone: > I am doing a scf calculation for my structure. My structure has 660 > atoms(56 H,324C,280 Si). I use H terminated Si-C surface. But after 24 > hours calculation(46 steps), the scf accuracy still fluctuate from about 1 > to 100. > Does anyone ever know this before?How to solve it? > Thank you very much!
You can try to: 1) browse the forum, the issue has been discussed many many times, there is not a unique answer the problem might be related to several issues 2) browse the QE wiki: http://www.quantum-espresso.org/wiki/index.php/Frequently_Asked_Questions#Self-consistency_is_slow_or_does_not_converge_at_all Did you check your geometry using, e.g., XCrysDen? Some times, mostly when dealing with such a huge number of atoms, a wrong coordinate might give atom overlap preventing the scf cycle from converging. You might also try to tune some parameters related to the convergence of the scf cycle, like mixing_beta. Giovanni -- Dr. Giovanni Cantele CNR-SPIN and Dipartimento di Scienze Fisiche Universita' di Napoli "Federico II" Complesso Universitario di Monte S. Angelo - Ed. 6 Via Cintia, I-80126, Napoli, Italy Phone: +39 081 676910 - Fax: +39 081 676346 ResearcherID: http://www.researcherid.com/rid/A-1951-2009 Web page: http://people.na.infn.it/~cantele Research Group: http://www.nanomat.unina.it Skype contact: giocan74
