Thank you!<br>It really help! I have solved the problem!<br>----- 原始邮件 -----<br>发件人：Giovanni Cantele <giovanni.cantele@na.infn.it><br>收件人：PWSCF Forum <pw_forum@pwscf.org><br>主题：Re: [Pw_forum] Graphene--Silicon Surface(scf not converge)<br>日期：2010-3-5 04:55:41<br><br><br>
> Hi everyone:<br>
> I am doing a scf calculation for my structure. My structure has 660<br>
> atoms(56 H,324C,280 Si). I use H terminated Si-C surface. But after 24<br>
> hours calculation(46 steps), the scf accuracy still fluctuate from about 1<br>
> to 100.<br>
> Does anyone ever know this before?How to solve it?<br>
> Thank you very much!<br>
<br>
You can try to:<br>
1) browse the forum, the issue has been discussed many many times, there<br>
is not a unique answer the problem might be related to several issues<br>
<br>
2) browse the QE wiki:<br>
<a href="http://www.quantum-espresso.org/wiki/index.php/Frequently_Asked_Questions#Self-consistency_is_slow_or_does_not_converge_at_all" target="_blank">http://www.quantum-espresso.org/wiki/index.php/Frequently_Asked_Questions#Self-consistency_is_slow_or_does_not_converge_at_all</a><br>
<br>
Did you check your geometry using, e.g., XCrysDen? Some times, mostly when<br>
dealing with such a huge number of atoms, a wrong coordinate might give<br>
atom overlap preventing the scf cycle from converging. You might also try<br>
to tune some parameters related to the convergence of the scf cycle, like<br>
mixing_beta.<br>
<br>
Giovanni<br>
<br>
-- <br>
Dr. Giovanni Cantele<br>
CNR-SPIN and Dipartimento di Scienze Fisiche<br>
Universita' di Napoli "Federico II"<br>
Complesso Universitario di Monte S. Angelo - Ed. 6<br>
Via Cintia, I-80126, Napoli, Italy<br>
Phone: +39 081 676910 - Fax:   +39 081 676346<br>
ResearcherID: <a href="http://www.researcherid.com/rid/A-1951-2009" target="_blank">http://www.researcherid.com/rid/A-1951-2009</a><br>
Web page: <a href="http://people.na.infn.it/%7Ecantele" target="_blank">http://people.na.infn.it/~cantele</a><br>
Research Group: <a href="http://www.nanomat.unina.it" target="_blank">http://www.nanomat.unina.it</a><br>
Skype contact: giocan74<br>
<br>
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