The ABINIT Users Mailing List ( CLOSED )

[Steven Homolya <steven.homolya@spme.monash.edu.au>]

Wu Rongqin wrote:
> Dear all,
>
> When I try to do calculation with B, O, and N pseudopotentials, I find 
> that the calculation cannot get converged. The pps are download from the 
> abinit website (TM-normconserving)
>
> And one can point out the problem? I changed k-mesh, ecut. But still failed.
>
>  

Reduce diemix and diemac (see help files). If that doesn't do it run at 
least 5 SCF cycles with iscf=3, then finish the calculation with the 
default iscf=5. You can of course just run with iscf=3 all the way, but 
I've found that very slow.

I've posted on this before, but the varbas.html help file still says 
(Abinit v 4.3):

"The preferred option is 5, which is quite robust. The value 3 can be 
faster, but sometimes the SCF iterations will not converge with iscf=3"

I consistently found that the opposite is true, i.e., iscf=5 is fast but 
not always reliable, and iscf=3 is safe but slow to converge (Abinit v. 
4.1 & 4.2).

Steve