[Pw_forum] charge is wrong: smearing is needed

[evan]

Dear GiuseppeI see. Thank you for your kind reply.

Fei Mao









At 2016-06-10 18:02:59, "Giuseppe Mattioli" <giuseppe.mattioli at ism.cnr.it> wrote:
>
>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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