[Pw_forum] Graphene--Silicon Surface(scf not converge)

[wulilixiangguo at sina.com]

 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!
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