[DFTB-Plus-User] SCC does not converge

[Bálint Aradi]

Dear Yang,

 > I always encounter the problem that the scc dos not converge for more
> than 800 steps. For a very simple case like a bare edge (9,0) carbon
> nanotube, when I try to relax the structure it never converged. Could
> anyone help me with that?

As you do not provide much details, hard to say what the problem is. As 
Argo Nurbawono already pointed out, setting an electronic temperature 
may help, especially when your system is metallic, as for those systems 
you have to use a finite filling temperature. You may play with the 
different filling functions. Probably Fermi is good enough, although for 
metals the Methessel-Paxton scheme is often used as well.

   Best regards,

     Bálint

-- 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b_aradi/