[Pw_forum] charge is wrong: smearing is needed

[Giuseppe Mattioli]

Dear Evan (sign always with full name, please)

You are not simulating an insulator LiF, you are simulating a LiF with an interstitial H that add one electron to the system, so that you have an even 
number of electrons. But you required a closed shell calculation. The code is not able to fit the excess electron in a closed shell orbital if you do 
not permit the treatment of the system as a "metal" by using one of the flavours of occupations='smearing'. You might also want to consider if nspin=2 
is more suitable in your case.
HTH
Giuseppe

On Friday, June 10, 2016 04:20:55 PM evan wrote:
> Dear all,
> 
> I am performing geometry optimization calculations on insulator LiF. For insulators with a gap, I read from the variable document and set
> ‘occupations = fixed’ in the input file (attached). However, at the end of one BFGS optimization step (contains 15 scf iterations), the error is
> followed (also attached):
> 
> 
> 
> %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> 
>      Error in routine electrons (1):
> 
>      charge is wrong: smearing is needed
> 
>  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
> 
> 
> 
> The error is self-explained, and it can be fixed by ‘occupations = smearing’, but it is conflict with what is said in the document.
> 
>  So, how to fix the problem. Your comments or suggestions are much appreciated.
> 
> Regards
> 
> Evan
> 
> University of South China, China

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   Giuseppe Mattioli                            
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